utils/build-galaxy-release.sh: Enable offline generation for rpm

Two new options have been added to enable the offline build within rpm:

    -o <A.B.C>  Build offline without using git, using version A.B.C
                Also enables -a
    -p <path>   Installation the generated collection in the path, the
                ansible_collections sub directory will be created and will
                contain the collection: ansible_collections/<namespace>/<name>
                Also enables -i

The usage text has been fixed also for specifying namespace and name.
The collection variable has been renamed to name.

Example usage:

    utils/build-galaxy-release.sh -o 1.12.1 \
        -p %{buildroot}%{_datadir}/ansible/collections \
        freeipa ansible_freeipa