Provide binary name for KSClassDeclaration in Resolver

I need the binary name corresponding to `KSClassDeclaration` in my processor, and would like to see this functionality added to ksp. The functionality is readily available from asm, but not currently exposed at the ksp API level. It is similar to what `Resolver.mapToJvmSignature()` provides, but for class binary names. It also is similar to `Resolver.getOwnerJvmClassName()`, without the part of finding the owner.

It may make sense to instead mirror `Resolver.mapToJvmSignature()` with `Resolver.mapToJvmClassName()`, making this functionality available for `KSClassDeclaration`, `KSFunctionDeclaration`, and `KSPropertyDeclaration`. I am not clear on the implementation in the latter two cases, while the first one is trivial.

I can provide a PR for the `KSClassDeclaration` case. I am not as clear on the `KSFunctionDeclaration` and `KSPropertyDeclaration` cases.