Genex $<COMPILE_LANGUAGE>: Extend contexts supported
When genex $<TARGET_PROPERTY:...> for properties like INCLUDE_DIRECTORIES is evaluated as part of add_custom_command or add_custom_target, genex $<COMPILE_LANGUAGE> and $<COMPLIE_LANG_AND_ID> should be supported.
Fixes: #20926 (closed)
Topic-rename: genx-COMPILE_LANGUAGE-support