feat: Only stop places checkbox in location search

[gorandalum]

Background

When looking at geocoder request logs, we see that only ~8% of
location searches end up in the user selecting an address. They
instead use my position or a stop place.

It was decided to do a proof of concept by swiftly adding a checkbox,
and get quick feedback on whether this is a feature that users will use
or not.

Solution

To make searching for stop places easier we add a checkbox the user
can check so only stop places are returned when searching for a
location. We will enable this to a subset of the users, and see if
it is a feature which will be used.

Acceptance criteria

• If the is not checked, both stop places and other locations are returned.
• If the checkbox is checked, then only stop places are returned.
• When toggling the checkbox, a PostHog event is sent ('Location search'/'Only stop places checkbox pressed').
• The checkbox is only shown if enable_only_stop_places_checkbox evaluates to true in RemoteConfig
• When using debug override, the setting in RemoteConfig is overridden

[marius-at-atb]

Lgtm!

[tormoseng]

Note to after release of 1.57:

• Make PostHog dashboard for event Location search: Only stop places checkbox pressed with cheked: true | false
• Look on Grafana for requests with layers=venue like /bff/v1/geocoder/features?lat=63.43119807409924&layers=venue&

[tormoseng]

✅ Tested OK!