Add the ABI files generated by libabigail abidw tool (note that
--no-corpus-path --no-comp-dir-path options were used to avoid having
system-specific object file paths in these files and the source file
paths were edited to remove the system-specific prefix from them too)
and a script comparing the current ABI with these files.
Also update the documentation to describe using libabigail tools as
abi-compliance-checker doesn't seem to work under the recent systems any
longer: it gives some warnings and doesn't detect ABI-incompatible
changes.
Closes#22634.
