Closes
https://linear.app/zed-industries/issue/Z-2735/make-inlay-hints-discoverable
Deals with https://github.com/zed-industries/community/issues/1764

Adds `editor::ToggleInlayHints` command and a new panel with two
buttons for 
* toggling hints on/off for every editor separately (overrides settings)

Would benefit from a new icon.

* toggling buffer search on/off 

Does not have a keybinding shown in its tooltip, that is a separate
issue with the way `KeystrokeLabel` gets these for panels not in the
view directly.

Release Notes:

- Adds `editor::ToggleInlayHints` command and a bar to toggle
editor-related items