Move git-related setup into hooks
Move git-related setup into hooks

Current Kakoune "always assume you're in the root directory" doesn't
really fit with my workflows (e.g., "Oh, need to edit something in my
dotfiles now"). Do some detection both to fit that better (not yet
wired up to the `:git` built-in commands), but also to prevent `:git
show-diff` when not in a git directory at all.

benizi/dotfiles,benizi/dotfiles,benizi/dotfiles,benizi/dotfiles,benizi/dotfiles,benizi/dotfiles,benizi/dotfiles,benizi/dotfiles