cmd L refactor

[RomneyDa]

Description

New cmd L logic (and bug fixes):

• Cmd + L:
  • if input is focused
    • if there's no chat history, toggle the GUI
    • otherwise start a new chat session and focus the input
  • otherwise
    • open the GUI
    • start a new chat session and focus the input
    • add any highlighted code
• Cmd + Shift + L
  • if input is focused, hide the GUI
  • otherwise, show the GUI, focus the input, and add any highlighted code

Checklist

• [x] The base branch of this PR is dev, rather than main
• [x] The relevant docs, if any, have been updated or created