feat: expose git_worktree telescope actions

[jamestrew]

Exposes delete_worktree and toggle_forced_deletion to uses via require('telescope').extensions.git_worktree.actions.[action_name].

This will enable users to rebind those actions to different keys easily.

I don't know why I didn't think to do this apart of #80 but if/once that gets merged in, people will be able to set mappings in the telescope setup() function. I can tweak the readme so show that when the time comes.

[jamestrew]

actually nevermind I can just put this as part of #80 and that'll save some trouble with rebasing, adding to readme.