Add online binary sensor & make device_tracker always available
Breaking Change
This is considered a breaking change since some automations, etc. may take certain steps when the Google Maps server becomes unavailable. This is still possible but will require using the new binary sensor instead.
What's Changed
Add an "online" binary sensor and make device_tracker entities always available, retaining their previous state, even when server dropouts occur.
This effectively moves the "server unavailable" status to an "out of band" signal. The way it was (i.e., "in band"), although the way the core team seems to think entities should work, makes the entities more difficult to use in automations, etc. Users often have to create template sensors and/or complicated conditions to ignore the "unavailable" state of these entities. This change makes them much easier to use, but still provides the server status, in case that is desired or necessary.
Also fix two problems. First, locationsharinglib was removed from manifest.json, breaking legacy configs. This change adds that back in. Second, due to some buggy device tracker component and entity registry code, this integration's entities may not appear after a HA restart. The buggy code was fixed in 2024.4. This change adds a workaround to avoid the problem for earlier HA versions.