Add SwiftLint rule to enforce stack spacing.

[pixlwave]

As part of #2007 I noticed that nested stack behaviour has changed when building with the new SDK. Whilst we're still waiting for a solution on the CI side, this PR adds SwiftLint rules to ensure all HStack and VStacks have the spacing parameter (and then goes through the codebase and fixes them by adding spacing and watching the preview to get the right value).

Some snapshots have changed as a result of preview stacks and so don't reflect changes in the app. There are some layout changes to the plain timeline style too:

• There was random trailing spacing meaning that items didn't line up with the trailing edge of the timestamp. This is now fixed.
• The spacing between the thread decorator, reply preview and message has ended up collapsing slightly. We don't have designs so there's nothing to go on here, but it helps pull all the content from the same message together to me.

[github-actions]

	Warnings
⚠️	Some of the commits are missing ticket numbers. Please consider squashing all commits that don't have a tracking number.
⚠️	You seem to have made changes to views. Please consider adding screenshots.

Generated by 🚫 Danger Swift against 8e54c43

[codecov]

Codecov Report

Attention: 5 lines in your changes are missing coverage. Please review.

Comparison is base (4257c20) 69.93% compared to head (57a6635) 69.90%.
Report is 1 commits behind head on develop.

❗ Current head 57a6635 differs from pull request most recent head 8e54c43. Consider uploading reports for the commit 8e54c43 to get more accurate results

Files	Patch %	Lines
...Sources/Other/MapLibre/MapLibreStaticMapView.swift	0.00%	1 Missing ⚠️
...ources/Other/SwiftUI/Layout/FullscreenDialog.swift	66.66%	1 Missing ⚠️
...oserToolbar/View/VoiceMessagePreviewComposer.swift	91.66%	0 Missing and 1 partial ⚠️
...mMemberListScreen/View/RoomMembersListScreen.swift	50.00%	1 Missing ⚠️
...KeyScreen/View/SecureBackupRecoveryKeyScreen.swift	90.90%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2080      +/-   ##
===========================================
- Coverage    69.93%   69.90%   -0.03%     
===========================================
  Files          518      518              
  Lines        36166    36139      -27     
  Branches     17525    17510      -15     
===========================================
- Hits         25292    25263      -29     
- Misses       10223    10224       +1     
- Partials       651      652       +1     

Flag	Coverage Δ
unittests	54.33% <95.72%> (-0.14%)	⬇️

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[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication