FindEXPAT: Fix for debug and other modified builds

Now considers debug builds, and various other build types which result in a modified library name. See: https://github.com/libexpat/libexpat/blob/0a69634eb45e4c169f9c85b03954f26eca61f49b/expat/CMakeLists.txt#L406-L437

Based on FindZLIB.

Fixes: #24422 (closed)
Topic-rename: FindEXPAT-multi-config