resolves #6103

BREAKING CHANGE: this removes branch properties from the git segment
and replaces them with a single template. To migrate, use the following
guide.

*branch_max_length*

`"branch_max_length": 5` -> `"branch_template": "{{ trunc 5 .Branch }}"`

This will turn `feature/test-this-branch` into `featu`

If you want to display a truncate symbol at the end of the branch name:

`"branch_template": "{{ truncE 5 .Branch }}"`

This will turn `feature/test-this-branch` into `feat…`

*full_branch_path*

`"full_branch_path": false` -> `"branch_template": "{{ base .Branch }}"`

This will turn `feature/test-this-branch` into `test-this-branch`

resolves #6149