Consume the context menu event instead of sending a mouse up

[StomyPX]

Relevant components:

• Signalling server
• Frontend library
• Frontend UI library
• Matchmaker
• Platform scripts
• SFU

Problem statement:

Right-Click dragging is presently impossible in hovering mouse mode as when the frontend receives a context menu event this gets instead sent as a right-mouse-up to Unreal Engine which is largely nonsensical.

Solution

This PR simply consumes the context menu event and allows UE to decide for itself when to open a context menu which it can already do reliably. In exchange, right-click dragging now works correctly.

Documentation

N/A

Test Plan and Compatibility

Simply launching an editor stream and testing out RMB-dragging in any viewport or node-graph shows the restored functionality.

[lukehb]

Approved. Can confer will @Belchy06 on which PSInfra branches this is relevant to merge back to down to (UE 5.3 at least seems relevant).

[github-actions]

💚 All backports created successfully

Status	Branch	Result
✅	UE5.2
✅	UE5.3

Note: Successful backport PRs will be merged automatically after passing CI.

Questions ?

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