[llvm][frontend][offloading] Move clang-linker-wrapper/OffloadWrapper.* to...

[llvm][frontend][offloading] Move clang-linker-wrapper/OffloadWrapper.* to llvm/Frontend/Offloading (#78057)

This patch moves `clang/tools/clang-linker-wrapper/OffloadWrapper.*` to
`llvm/Frontend/Offloading` allowing them to be re-utilized by other
projects.

Additionally, it makes minor modifications to the API to make it more
flexible.
Concretely:
 - The `wrap*` methods now have additional arguments `EntryArray`, 
`Suffix` and `EmitSurfacesAndTextures` to specify some additional options.
- The `EntryArray` is now constructed by the caller. This change is needed to
enable JIT compilation, as ORC doesn't fully support `__start_` and `__stop_` 
symbols. Thus, to JIT the code, the `EntryArray` has to be constructed explicitly in the IR.
- The `Suffix` field is used when emitting the descriptor, registration
methods, etc, to make them more readable. It is empty by default.
- The `EmitSurfacesAndTextures` field controls whether to emit surface
and texture registration code, as those functions were removed from `CUDART`
in CUDA 12. It is true by default.
- The function `getOffloadingEntryInitializer` was added to help create
the `EntryArray`, as it returns the constant initializer and not a global
variable.