debuginfo-install: use srpm basename for debuginfo

When we trying to install debuginfo for subpackage (e.g.
gedit-plugin-charmap) we should install debuginfo for main package (e.g.
gedit-plugins), but we didn't it before. Let's fix it!
debuginfo-install: fix indenting
copr: implement help command

When we have not help command and people typing `dnf copr help` they
getting annoying error, that them want to use >2 args.