2948: Start a new chat for each region

[steffenkleinle]

Short description

Start a new chat for each region instead of sharing the chat instance.
This would break the chat in the backend.

Proposed changes

Store the id of the chat in the local storage related to the city.

Side effects

⚠️ Previous chats won't work anymore (unless the chat id is copied manually to the new local storage entry).

Testing

Open the chat in testumgebung and send a message.
Then go to muenchen and open the chat and confirm that there is no chat yet.

Resolved issues

Fixes: #2948, digitalfabrik/integreat-chat#54.

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[steffenkleinle]

⚠️ @svenseeberg Previous chats won't work anymore after this PR is released to production (unless the chat id is copied manually to the new local storage entry).
Do you think we have to notify any of our testers of that?

[LeandraH]

Nice, tested in Firefox

[ztefanie]

Tested on firefox and chrome 👍

[codeclimate]

Code Climate has analyzed commit 9535b0a and detected 0 issues on this pull request.

The test coverage on the diff in this pull request is 100.0% (50% is the threshold).

This pull request will bring the total coverage in the repository to 74.2%.

View more on Code Climate.

[svenseeberg]

Previous chats won't work anymore after this PR is released to production

This is totally fine. We are currently in an alpha stage and breaking changes are totally acceptable.