Reporting: emit report dates as clean invariant ISO-8601

The CSV and XML report generators format DateTime through FormatExtensions.Format, which previously
delegated to Ecng's Converter.To<string>. After the Ecng update that started returning a
culture-invariant string the old culture-dependent golden fixtures (1/1/2024 12:00:00 AM) stopped
matching, and the full round-trip form it produced (2024-01-01T00:00:00.0000000Z) was verbose and
inconsistent with the JSON report.

Format the value explicitly as invariant ISO-8601 with "yyyy-MM-ddTHH:mm:ss.FFFFFFFK": the leading
'.' and the fractional digits are emitted only for a non-zero fraction, so whole-second values render
as 2024-01-15T10:00:00Z and all three report formats agree. Regenerate the CSV and XML golden fixtures
accordingly; the JSON fixture already used ISO and is unchanged.

Author: mikasoukhov

Reporting/FormatExtensions.cs

@@ -1,5 +1,7 @@
 namespace StockSharp.Reporting;
 
+using System.Globalization;
+
 /// <summary>
 /// Format extensions.
 /// </summary>
@@ -27,5 +29,8 @@ public static string Format(this TimeSpan time)
 	/// <param name="time"><see cref="DateTime"/> value.</param>
 	/// <returns><see cref="string"/>.</returns>
 	public static string Format(this DateTime time)
-		=> time.To<string>();
+		// Invariant ISO-8601. The leading '.' before the 'F' specifiers is emitted only when the
+		// fractional part is non-zero, and trailing zero digits are trimmed, so whole-second values
+		// render as 2024-01-15T10:00:00Z - matching the JSON report representation.
+		=> time.ToString("yyyy-MM-ddTHH:mm:ss.FFFFFFFK", CultureInfo.InvariantCulture);
 }

Tests/Resources/Reports/expected_report.csv

@@ -2,18 +2,18 @@ Strategy,Working time,Position,P&L,Commission,Slippage,Latency
 TestStrategy,08:00:00,100,5000,25,1.5,00:00:00
 Parameters
 Symbol,TimeFrame,StartDate,Volume,IsLong,MaxPositions
-BTCUSD,00:05:00,1/1/2024 12:00:00 AM,100,True,5
+BTCUSD,00:05:00,2024-01-01T00:00:00Z,100,True,5
 Statistics
 WinRate,MaxDrawdown,TradesCount,AverageTradeTime,BestTradeDate,SharpeRatio
-0.65,-500,42,00:15:00,1/15/2024 2:30:00 PM,1.85
+0.65,-500,42,00:15:00,2024-01-15T14:30:00Z,1.85
 Orders
 Identifier,Transaction,Security,Direction,Time,Price,Status,Balance,Volume,Type
-1,100,BTCUSD@CRYPTO,Buy,1/15/2024 10:00:00 AM,50000,Done,0,1,Limit
-2,101,BTCUSD@CRYPTO,Sell,1/15/2024 11:00:00 AM,50500,Done,0,1,Limit
+1,100,BTCUSD@CRYPTO,Buy,2024-01-15T10:00:00Z,50000,Done,0,1,Limit
+2,101,BTCUSD@CRYPTO,Sell,2024-01-15T11:00:00Z,50500,Done,0,1,Limit
 Trades
 Identifier,Transaction,Security,Time,Price,Volume,Direction,Order ID,P&L,Slippage
-1001,100,BTCUSD@CRYPTO,1/15/2024 10:00:00 AM,50000,1,Buy,1,0,0
-1002,101,BTCUSD@CRYPTO,1/15/2024 11:00:00 AM,50500,1,Sell,2,500,0
+1001,100,BTCUSD@CRYPTO,2024-01-15T10:00:00Z,50000,1,Buy,1,0,0
+1002,101,BTCUSD@CRYPTO,2024-01-15T11:00:00Z,50500,1,Sell,2,500,0
 Positions
 Security,Portfolio,Entry Time,Opening Price,Exit Time,Closing Price,Max volume
-BTCUSD@CRYPTO,TestPortfolio,1/15/2024 10:00:00 AM,50000,1/15/2024 11:00:00 AM,50500,1
+BTCUSD@CRYPTO,TestPortfolio,2024-01-15T10:00:00Z,50000,2024-01-15T11:00:00Z,50500,1

Tests/Resources/Reports/expected_report.xml

@@ -3,7 +3,7 @@
   <parameters>
     <parameter name="Symbol" value="BTCUSD" />
     <parameter name="TimeFrame" value="00:05:00" />
-    <parameter name="StartDate" value="1/1/2024 12:00:00 AM" />
+    <parameter name="StartDate" value="2024-01-01T00:00:00Z" />
     <parameter name="Volume" value="100" />
     <parameter name="IsLong" value="True" />
     <parameter name="MaxPositions" value="5" />
@@ -13,18 +13,18 @@
     <parameter name="MaxDrawdown" value="-500" />
     <parameter name="TradesCount" value="42" />
     <parameter name="AverageTradeTime" value="00:15:00" />
-    <parameter name="BestTradeDate" value="1/15/2024 2:30:00 PM" />
+    <parameter name="BestTradeDate" value="2024-01-15T14:30:00Z" />
     <parameter name="SharpeRatio" value="1.85" />
   </statistics>
   <orders>
-    <order id="1" transactionId="100" securityId="BTCUSD@CRYPTO" direction="Buy" time="1/15/2024 10:00:00 AM" price="50000" state="Done" balance="0" volume="1" type="Limit" />
-    <order id="2" transactionId="101" securityId="BTCUSD@CRYPTO" direction="Sell" time="1/15/2024 11:00:00 AM" price="50500" state="Done" balance="0" volume="1" type="Limit" />
+    <order id="1" transactionId="100" securityId="BTCUSD@CRYPTO" direction="Buy" time="2024-01-15T10:00:00Z" price="50000" state="Done" balance="0" volume="1" type="Limit" />
+    <order id="2" transactionId="101" securityId="BTCUSD@CRYPTO" direction="Sell" time="2024-01-15T11:00:00Z" price="50500" state="Done" balance="0" volume="1" type="Limit" />
   </orders>
   <trades>
-    <trade id="1001" transactionId="100" securityId="BTCUSD@CRYPTO" time="1/15/2024 10:00:00 AM" price="50000" volume="1" order="1" PnL="0" slippage="0" />
-    <trade id="1002" transactionId="101" securityId="BTCUSD@CRYPTO" time="1/15/2024 11:00:00 AM" price="50500" volume="1" order="2" PnL="500" slippage="0" />
+    <trade id="1001" transactionId="100" securityId="BTCUSD@CRYPTO" time="2024-01-15T10:00:00Z" price="50000" volume="1" order="1" PnL="0" slippage="0" />
+    <trade id="1002" transactionId="101" securityId="BTCUSD@CRYPTO" time="2024-01-15T11:00:00Z" price="50500" volume="1" order="2" PnL="500" slippage="0" />
   </trades>
   <positions>
-    <position securityId="BTCUSD@CRYPTO" portfolio="TestPortfolio" openTime="1/15/2024 10:00:00 AM" openPrice="50000" closeTime="1/15/2024 11:00:00 AM" closePrice="50500" maxPosition="1" />
+    <position securityId="BTCUSD@CRYPTO" portfolio="TestPortfolio" openTime="2024-01-15T10:00:00Z" openPrice="50000" closeTime="2024-01-15T11:00:00Z" closePrice="50500" maxPosition="1" />
   </positions>
 </strategy>