Add rendezvous service (MSC3886) and ECDH X25519 AES 256 based secure…

[stefanceriu]

… channel creation establishing implementation and simple tests.

This PR implements:

• MSC3886: Simple client rendezvous capability
• MSC3903: X25519 Elliptic-curve Diffie-Hellman ephemeral for establishing secure channel between two Matrix clients

[codecov]

Codecov Report

Base: 52.10% // Head: 6.05% // Decreases project coverage by -46.05% ⚠️

Coverage data is based on head (5b2a0cc) compared to base (4eb7a87).
Patch coverage: 46.91% of modified lines in pull request are covered.

Additional details and impacted files

@@             Coverage Diff              @@
##           develop    #6806       +/-   ##
============================================
- Coverage    52.10%    6.05%   -46.06%     
============================================
  Files          377     1513     +1136     
  Lines        14552   152561   +138009     
  Branches      5911    61518    +55607     
============================================
+ Hits          7583     9240     +1657     
- Misses        6786   142913   +136127     
- Partials       183      408      +225     

Impacted Files	Coverage Δ
Riot/Modules/Rendezvous/RendezvousTransport.swift	0.00% <0.00%> (ø)
...t/Modules/Rendezvous/MockRendezvousTransport.swift	74.19% <74.19%> (ø)
Riot/Modules/Rendezvous/RendezvousService.swift	77.02% <77.02%> (ø)
Riot/Categories/Character.swift	0.00% <0.00%> (-100.00%)	⬇️
...otSwiftUI/Modules/Common/Util/BorderModifier.swift	0.00% <0.00%> (-100.00%)	⬇️
...iftUI/Modules/Common/Avatar/Model/Avatarable.swift	0.00% <0.00%> (-100.00%)	⬇️
...iftUI/Modules/Common/Util/RoundedCornerShape.swift	0.00% <0.00%> (-100.00%)	⬇️
...odules/AnalyticsPrompt/AnalyticsPromptModels.swift	0.00% <0.00%> (-100.00%)	⬇️
...odules/Common/DependencyInjection/Injectable.swift	0.00% <0.00%> (-100.00%)	⬇️
...dules/Common/Theme/ThemeUsersColorsExtension.swift	0.00% <0.00%> (-100.00%)	⬇️
... and 1414 more

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[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
No Duplication information

[ismailgulek]

LGTM. It seems we can inject the RendezvousService into the QRLoginService and update the service state accordingly after some actions. Feel free to replace QRLoginCode with your RendezvousPayload.

Also ftr on matrix-js-sdk it seems the payload updated with an intent: https://github.com/matrix-org/matrix-js-sdk/blob/hughns/http-rendezvous/src/rendezvous/code.ts