pygmt.show_versions: Warn about incompatible ghostscript versions

[seisman]

Description of proposed changes

1. Add a private function _get_clib_info to return the dictionary of GMT library information
2. Refactor _get_ghostscript_version using match-case statement
3. Add a private function _check_ghostscript_version which return warnings if the installed ghostscript version is problematic
4. Store the output in a list and print it, rather than calling print multiple times.

Address #3242

[seisman]

The pygmt.print_clib_info function was initially added in #176 but has been replaced by pygmt.show_versions in #466 (first appear in v0.1.2).

In this PR, a new private function _get_clib_info is added which returns a dictionary instead of printing a long string.

It's time to retire the print_clib_info function. Since it's rarely used, I think we can just remove it without a deprecation warning. Of course, we should do it in a separate PR so that at least we have a deprecation entry in the v0.13.0 changelog.