Add more options for git flow

[silmaril42]

I'd love to have more options available when finishing features or releases using git flow.
The most important arguments I'd like to have:

• --push Push to origin after performing finish
• --squash Squash feature / release during merge

There are more options available (see git flow feature finish --help / git flow release finish --help), but I think those two are the most important ones. Implementing others might get more complex than just adding two checkboxes.

[love-linger]

Done. You can download the latest CI build from Github Action.

[silmaril42]

Wow, that was quick!

Thank you very much! :-)