Improve avatar rendering

[ganfra]

Content

This PR takes care of using a single thumbnail request size, so caching works properly.
Indeed, according to the matrix specs :

Servers SHOULD produce thumbnails with the following dimensions and methods:
32x32, crop
96x96, crop
320x240, scale
640x480, scale
800x600, scale

For rendering avatar we could use crop, but it's not available in the rust sdk yet.
So instead, always use the smallest scale function ie. requesting with a size <= 240 pixels would makes sure we do.

This way, we'll be hitting the server only once per mxc url, and not for each size we've defined in our AvatarSize.

Motivation and context

Improve rendering by removing useless network calls.

Screenshots / GIFs

Tests

• Step 1
• Step 2
• Step ...

Tested devices

• Physical
• Emulator
• OS version(s):

Checklist

• Changes have been tested on an Android device or Android emulator with API 23
• UI change has been tested on both light and dark themes
• Accessibility has been taken into account. See https://github.com/element-hq/element-x-android/blob/develop/CONTRIBUTING.md#accessibility
• Pull request is based on the develop branch
• Pull request title will be used in the release note, it clearly define what will change for the user
• Pull request includes screenshots or videos if containing UI changes
• Pull request includes a sign off
• You've made a self review of your PR

[github-actions]

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[jmartinesp]

LGTM, thanks!

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[codecov]

Codecov Report

Attention: Patch coverage is 28.57143% with 5 lines in your changes missing coverage. Please review.

Project coverage is 82.83%. Comparing base (366db47) to head (2e631b1).
Report is 3 commits behind head on develop.

Files with missing lines	Patch %	Lines
...roid/libraries/matrix/ui/media/CoilMediaFetcher.kt	0.00%	2 Missing ⚠️
.../libraries/matrix/ui/media/ImageLoaderFactories.kt	0.00%	2 Missing ⚠️
...droid/libraries/matrix/ui/media/AvatatarDataExt.kt	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #3642   +/-   ##
========================================
  Coverage    82.82%   82.83%           
========================================
  Files         1747     1747           
  Lines        41742    41737    -5     
  Branches      5102     5102           
========================================
  Hits         34572    34572           
+ Misses        5355     5350    -5     
  Partials      1815     1815           

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