Add Timezone sharing

[Airyzz]

Description

Adds the ability for a user to append their local time zone to the room state.

In direct messages, Cinny will display the local time of the user you are talking to in a banner, if they have shared their timezone
( #620 )

This is implemented by sending an event in.cinny.share_timezone to a room, and then appending the id of that event to the room state under in.cinny.shared_timezone where the sender's name is the state key.

share_timezone event:

{
  "user_timezone": "Asia/Jakarta"
  "msgtype": "in.cinny.share_timezone"
}

shared_timezone room state event:

{
  "user_timezone_event": <event_id>
}

It is implemented in this way, so that the timezone information can be shared with an (encrypted, if room is encrypted) event, and since the event id is in the room state, it can be easily found.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings

Preview: https://810--pr-cinny.netlify.app
⚠️ Exercise caution. Use test accounts. ⚠️

[Airyzz]

Converted this to a draft, I want to change this so timezones are shared with e2ee

[ajbura]

closing as not plained