Add configuration.statuses.max_characters to initial_state from instance api on frontend

[sinoru]

Using instance api's configuration.statuses.max_characters on frontend to evaluate character limit.

This will fixes some tiny parts of #12265.

[ClearlyClaire]

I am not sure this is the best way to go as the server configuration is not fetched immediately.

See also #27629 which has another approach to passing the character limit down.

[sinoru]

I am not sure this is the best way to go as the server configuration is not fetched immediately.

See also #27629 which has another approach to passing the character limit down.

@ClearlyClaire Ooops, I didn't know about #27629 PR and initialState things...

How do you think about #27833?
If it is okay-ish, I can close this PR, and make #27833 suitable for or base on (If @shleeable agrees) #27629.

[sinoru]

Changes to use initial_state and matching to InstanceSerializer (api/*/instance) for future-proof to add additional values to use on frontend.

[github-actions]

This pull request has merge conflicts that must be resolved before it can be merged.

[mjankowski]

Closing because I think #28928 does effectively same thing.

If I'm missing something here, please rebase, re-open, explain, etc...