Handled additional Range constructor in toSigners side condition. (#944)

This PR replaces the `allKeys` condition in the requires clause of
`toSigners` with another function, `allRangeWrappedKeys`, that works in
exactly the same way except is unwraps an additional Range constructor
from the provided `ListItem`. This `Range` is generated from `fromKey`,
and the existing `allKeys` implementation was not sufficient to handle
it, as it was expecting just a List.

The issue came up when investigating the failure of the proof for
test_process_initialize_multisig2. I attach a file that contains a part
of the stuck configuration, where I isolated a term that shows the
issue. The relevant term is `SignersError(...)`. With this change, the
proof was able to pass.

[signers-error.txt](https://github.com/user-attachments/files/25424362/signers-error.txt)

Note: I chose to use a new function rather than extend the functionality
of `allKeys` beyond its (apparent) intend to handle Lists, but I believe
that the issue could be solved with just another rule in `allKeys`, if
that is what you prefer.

Author: mariaKt

kmir/src/kmir/kdist/mir-semantics/symbolic/p-token.md

@@ -130,7 +130,7 @@ This ensures that branches on the key value are not duplicated.
 
   syntax Signers ::= toSigners ( Value ) [function, total]
   // -----------------------------------------------------
-  rule toSigners(Range(ELEMS)) => Signers( toKeys(ELEMS) ) requires size(ELEMS) ==Int 11 andBool allKeys(ELEMS)
+  rule toSigners(Range(ELEMS)) => Signers( toKeys(ELEMS) ) requires size(ELEMS) ==Int 11 andBool allRangeWrappedKeys(ELEMS)
   rule toSigners(VAL) => SignersError(VAL) [owise]
 
   syntax Value ::= fromSigners ( Signers ) [function, total]
@@ -155,6 +155,12 @@ This ensures that branches on the key value are not duplicated.
   rule allKeys( .List ) => true
   rule allKeys( ListItem(ELEMS) REST:List ) => allKeys(REST) requires size(ELEMS) ==Int 32 andBool allBytes(ELEMS)
   rule allKeys( ListItem(_OTHER) _:List )   => false [owise]
+
+  syntax Bool ::= allRangeWrappedKeys ( List ) [function, total]
+  // -----------------------------------------------------------
+  rule allRangeWrappedKeys( .List ) => true
+  rule allRangeWrappedKeys( ListItem(Range(ELEMS)) REST:List ) => allRangeWrappedKeys(REST) requires size(ELEMS) ==Int 32 andBool allBytes(ELEMS)
+  rule allRangeWrappedKeys( ListItem(_OTHER) _:List )   => false [owise]
 ```
 
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