ILVerify: Use case-insensitive comparer for assembly binding cache (#132108)

ILVerify assembly binding should runtime assembly binding that is
case-insensitive.

This is fixing a non-obvious failure mode caused by mismatched casing
for `--system-module` ILVerify argument. We ended up loading the system
module multiple times with different casing.

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Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Author: jkotas

src/coreclr/tools/ILVerify/Program.cs

@@ -18,7 +18,7 @@ namespace ILVerify
 {
     internal sealed class Program : IResolver
     {
-        private readonly Dictionary<string, PEReader> _resolverCache = new();
+        private readonly Dictionary<string, PEReader> _resolverCache = new(StringComparer.OrdinalIgnoreCase);
         private readonly ILVerifyRootCommand _command;
         private readonly Dictionary<string, string> _inputFilePaths; // map of simple name to file path
         private readonly Dictionary<string, string> _referenceFilePaths; // map of simple name to file path