sdk: add support for listening to stream of live location updates

[torrybr]

Conversation related to this issue can be found here

This merge request adds subscribe_to_live_location_shares to the matrix_sdk::Room that allows clients to listen for beacon updates using a background task. The method provides an easy way to subscribe to live location sharing events within a room, handling event processing internally.

Follow-up tasks will include adding support for the event cache.

[stefanceriu]

Seems that the test aren't particularly happy with this PR. Can you please have a look?

[Hywan]

Thanks for the PR. I've left some feedback that can impact the global design of your patch.

[codecov]

Codecov Report

Attention: Patch coverage is 91.30435% with 2 lines in your changes missing coverage. Please review.

Project coverage is 84.85%. Comparing base (8865e2f) to head (7f2d7a6).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/matrix-sdk/src/room/mod.rs	91.30%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4025      +/-   ##
==========================================
- Coverage   84.89%   84.85%   -0.05%     
==========================================
  Files         272      272              
  Lines       29167    29187      +20     
==========================================
+ Hits        24761    24766       +5     
- Misses       4406     4421      +15     

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