vcs_menu: Query branches on open instead of per keystroke (#3144)

Release Notes:

- Improved performance of branch picker by querying branches on menu
open instead of querying once per each keystroke. (fixes
zed-industries/community#2161)
fc37abc356Piotr Osiewicz committed on 10/21/2023, 12:01:01 PM· committed by GitHubparent2663874
4 files changedLine totals unavailable