Semantic branch shortening

[nojhan]

Allow to shorten long VCS branch names.

Description

Basics: if the branch name is too long, shorten it:

• fix-stuff-for-pre-release -> fix-stuff…release

Advanced: shortening takes into account semantic branch naming (i.e. preserve the type and the target).

• fix(frontend)-this-bug -> fix(stuff)…-bug

[Rycieos]

This is a good idea, but it will need a lot of work. Path shortening is by far the most complicated part of Liquidprompt, and I expect this to be quite complicated as well.

Probably should be configurable with the maximum length like LP_PATH_LENGTH.

Maybe we should throw out more examples, which can serve as both test cases as well as user stories for how we want this to work. And also just more user stories.

I'll start:

bugfix/a-weird-bug-i-once-found -> bugfix/…once-found  # keep everything up to the slash regardless.
feature/#728-semantic-branch-shortening -> feature/#728…  # maybe the beginning of the branch is more helpful.