clean sugar git

[amtoine]

related to

• https://github.com/amtoine/nu-git-manager/issues/106

description

this is an effort to

• [x] update the nu-git-manager-sugar git module
• [x] remove deprecated / useless commands
• [x] expose the meaningful ones as subcommands of gm
• [x] add tests when possible

kept commands

• get commit -> gm repo get commit
• root -> gm repo goto root
• branches -> gm repo branches
• is-ancestor -> gm repo is-ancestor
• remote list -> gm repo remote list

removed commands

• operations
• compare
• lock clean
• remote add
• remote remove
• fixup

tests

a new tests sugar git module with

• get-commit
• goto-root
• branches
• is-ancestor
• remote-list