Let clients pin favorite devices, exit nodes, and services so GUIs can
surface & change them. Pins are stored per login profile in the new
favorites feature module, keyed per category; devices and exit nodes by
StableNodeID, services by ServiceName.
The item types live in a leaf package feature/favorites/pintype,
keeping them out of the core ipn hierarchy. Each category has
its own type (pintype.Device, pintype.ExitNode, pintype.Service).
Exposed over LocalAPI at GET/POST /localapi/v0/pins, where POST replaces
only the categories named in the request so a client can update one
category without clobbering the others. Pins are local to the device and
are not synced across a user's devices.
updates tailscale/corp#44836
Signed-off-by: Will Hannah <willh@tailscale.com>
Co-authored-by: Will Hannah <wph@Wills-Virtual-Machine.local>
