[allergo5] Export cmake targets, disable install pdbs to lib

[JackBoosY]

This PR will:

• Export all allegro5 cmake targets:

The package allegro5:x86-windows provides CMake targets:

    find_package(unofficial-allegro5 CONFIG REQUIRED)
    # Note: 9 target(s) were omitted.
    target_link_libraries(main PRIVATE unofficial-allegro5::allegro unofficial-allegro5::allegro_ttf unofficial-allegro5::allegro_font unofficial-allegro5::allegro_main)

• Remove cmake code about the pdbs (introduced in Add ports for libmikmod and allegro5 #1466).
• Disable install all pdbs to lib and debug/lib folder.

Closes #17108 #17055

Already tested the usage.

[ras0219-msft]

This LGTM after my two suggestions are applied.

[ras0219-msft]

Thanks!