Replace locationsharinglib, reorg code & other misc improvements (#19)

Create replacement for locationsharinglib which more directly implements capabilities needed/used by integration.
Migrate configuration entry from version 1 to 2.
Add note to README.md about purging history of legacy trackers.
Remove support for initial beta versions when it comes to how entities are restored.
Write cookies & parsed data to log when invalid session indicated.
When loading new cookies file, store in newly named file in `.storage/google_maps` instead of overwriting existing file. This makes code much cleaner. Existing file will be deleted when config is reloaded.
Reorganize code to simplify, creating new helpers & coordinator modules.

README.md

@@ -324,3 +324,7 @@ If/when any "legacy" trackers are no longer desired, they can be removed from th
 2. Removing associated entries in `known_devices.yaml`.
 If that would make the file empty, then the file can simply be deleted instead.
 3. Restarting Home Assistant.
+
+Note that there will still be history for the legacy trackers, at least for a while.
+You can purge that history via the `recorder.purge_entities` service.
+See the [Recorder](https://www.home-assistant.io/integrations/recorder/) integration documentation for more details.