feat(proxy): add basic HTTP proxy configuration options

- Introduces `BasicHttpProxyOptions` for configuring HTTP proxies, including options for address, credentials, and bypass rules.
- Adds `NetworkCredentialOptions` for managing authentication details.
- Implements extension method `BuildBasicHttpProxy` to create `IWebProxy` instances from the new configuration options.

Renames existing extension namespaces for better organization.

Author: winromulus

src/ES.FX/Net/BasicHttpProxyOptions.cs

@@ -0,0 +1,39 @@
+using JetBrains.Annotations;
+
+namespace ES.FX.Net;
+
+/// <summary>
+/// Represents configuration options for an HTTP proxy, 
+/// including address, bypass rules, credential usage, and authentication details.
+/// </summary>
+[PublicAPI]
+public class BasicHttpProxyOptions
+{
+    /// <summary>
+    /// Gets or sets the URI address of the proxy server.
+    /// Example: <c>http://proxy.example.com:8080</c>.
+    /// </summary>
+    public string? Address { get; set; }
+
+    /// <summary>
+    /// Gets or sets a value indicating whether to bypass the proxy server for local addresses.
+    /// </summary>
+    public bool BypassProxyOnLocal { get; set; }
+
+    /// <summary>
+    /// Gets or sets the list of addresses that should bypass the proxy server.
+    /// Wildcard patterns can be used.
+    /// </summary>
+    public string[]? BypassList { get; set; }
+
+    /// <summary>
+    /// Gets or sets a value indicating whether the default system credentials should be used for authentication with the proxy server.
+    /// </summary>
+    public bool UseDefaultCredentials { get; set; }
+
+    /// <summary>
+    /// Gets or sets the network credentials to use for authenticating with the proxy server.
+    /// If <see cref="UseDefaultCredentials"/> is <c>false</c> and credentials are provided, these will be used.
+    /// </summary>
+    public NetworkCredentialOptions? Credentials { get; set; }
+}

src/ES.FX/Net/Extensions/WebProxyExtensions.cs

@@ -0,0 +1,34 @@
+using System.Net;
+using JetBrains.Annotations;
+
+namespace ES.FX.Net.Extensions;
+
+[PublicAPI]
+public static class WebProxyExtensions
+{
+    /// <summary>
+    /// Builds an <see cref="IWebProxy"/> instance from the specified <see cref="BasicHttpProxyOptions"/>.
+    /// </summary>
+    /// <param name="options">The proxy options to use for building the proxy.</param>
+    /// <returns>A configured <see cref="IWebProxy"/> instance, or <c>null</c> if no address is specified.</returns>
+    public static IWebProxy? BuildBasicHttpProxy(this BasicHttpProxyOptions? options)
+    {
+        if (options == null || string.IsNullOrWhiteSpace(options.Address))
+            return null;
+
+        var proxy = new WebProxy(options.Address)
+        {
+            BypassProxyOnLocal = options.BypassProxyOnLocal,
+            BypassList = options.BypassList ?? [],
+            UseDefaultCredentials = options.UseDefaultCredentials,
+            Credentials = options.Credentials is not null
+                ? new NetworkCredential(
+                    options.Credentials.UserName,
+                    options.Credentials.Password,
+                    options.Credentials.Domain)
+                : null
+        };
+
+        return proxy;
+    }
+}

src/ES.FX/Net/NetworkCredentialOptions.cs

@@ -0,0 +1,28 @@
+using JetBrains.Annotations;
+
+namespace ES.FX.Net
+{
+    /// <summary>
+    /// Represents configuration options for network credentials,
+    /// including username, password, and optional domain information.
+    /// </summary>
+    [PublicAPI]
+    public class NetworkCredentialOptions
+    {
+        /// <summary>
+        /// Gets or sets the username associated with the credentials.
+        /// </summary>
+        public string? UserName { get; set; }
+
+        /// <summary>
+        /// Gets or sets the password associated with the credentials.
+        /// </summary>
+        public string? Password { get; set; }
+
+        /// <summary>
+        /// Gets or sets the domain associated with the credentials.
+        /// Used primarily for NTLM or Kerberos authentication.
+        /// </summary>
+        public string? Domain { get; set; }
+    }
+}

src/ES.FX/Primitives/EnumExtensions.cs …/Primitives/Extensions/EnumExtensions.cssrc/ES.FX/Primitives/EnumExtensions.cs renamed to src/ES.FX/Primitives/Extensions/EnumExtensions.cs src/ES.FX/Primitives/EnumExtensions.cs renamed to src/ES.FX/Primitives/Extensions/EnumExtensions.cs

@@ -1,6 +1,6 @@
 using JetBrains.Annotations;
 
-namespace ES.FX.Primitives;
+namespace ES.FX.Primitives.Extensions;
 
 [PublicAPI]
 public static class EnumExtensions

src/ES.FX/Primitives/StringExtensions.cs …rimitives/Extensions/StringExtensions.cssrc/ES.FX/Primitives/StringExtensions.cs renamed to src/ES.FX/Primitives/Extensions/StringExtensions.cs src/ES.FX/Primitives/StringExtensions.cs renamed to src/ES.FX/Primitives/Extensions/StringExtensions.cs

@@ -2,7 +2,7 @@
 using System.Globalization;
 using JetBrains.Annotations;
 
-namespace ES.FX.Primitives;
+namespace ES.FX.Primitives.Extensions;
 
 [PublicAPI]
 public static class StringExtensions