Fix 'operator ==' is ambiguous with MSVC (#19501)

When compiling with MSVC on Windows, this error among other similar
conflicts with AnyValue occur:

Defined the overloads so it selects the correct one.

Author: Jason Mittertreiner

include/swift/AST/Type.h

@@ -592,6 +592,10 @@ class CanGenericSignature {
   GenericSignature *getPointer() const {
     return Signature;
   }
+
+  bool operator==(const swift::CanGenericSignature& other) {
+    return Signature == other.Signature;
+  }
 };
 
 template <typename T>

include/swift/SIL/SILValue.h

@@ -134,6 +134,10 @@ struct ValueOwnershipKind {
 
   operator innerty() const { return Value; }
 
+  bool operator==(const swift::ValueOwnershipKind::innerty& b) {
+    return Value == b;
+  }
+
   Optional<ValueOwnershipKind> merge(ValueOwnershipKind RHS) const;
 
   bool isTrivialOr(ValueOwnershipKind Kind) const {

lib/SILGen/SILGenApply.cpp

@@ -4558,7 +4558,7 @@ RValue SILGenFunction::emitApply(ResultPlanPtr &&resultPlan,
   }
 
   // Emit the raw application.
-  auto genericSig =
+  GenericSignature *genericSig =
     fn.getType().castTo<SILFunctionType>()->getGenericSignature();
 
   // When calling a closure that's defined in a generic context but does not