[Location sharing] - Small improvements of UI for live

[mnaturel]

Your use case

What would you like to do?

• Centre vertically the title and icon in the loading and ended state item in the timeline (due to the fact the map does not take the whole place in height on some devices).
• For active live item, make sure that the STOP button has 12dp padding on each side. This will act as a reference point for truncation of the title. Title should be ellipsized when too long.
• Message preview in a reply to a live location sharing message: “Live Location”
• On Dark theme, on some devices the loading/ended state map isn’t the right colour. Check guide here: https://www.figma.com/file/uthEK6xuo9hSQRdWvPAre5/Location-Sharing?node-id=470%3A51660

Why would you like to do it?

To improve the UX.

How would you like to achieve it?

Have you considered any alternatives?

No response

Additional context

No response

Are you willing to provide a PR?

Yes