RUM-6224 [Session Replay FGM] Create privacy overrides

[mariedm]

What and why?

This PR introduces the ability to override Session Replay's fine-grained privacy settings (text and input, images, touches) at the view level. This allows customers to apply specific privacy levels to specific views, overriding the global privacy configuration, enabling customers to control masking at a more granular level.

A new HiddenPrivacyLevel is also introduced, which, when applied to a view, will replace the view with an opaque wireframe and prevent any interactions or subviews from being recorded. This privacy level is only available as an override and takes precedence over other privacy settings.

How?

• Created a HiddenPrivacyLevel enum
• Added a SessionReplayOverride struct to encapsulate all overrideable privacy settings
• Created an extension for UIView to access SessionReplayOverride via the .dd.sessionReplayOverride property
• Used associated objects to store the privacy overrides for each view
• Created a separate set of enums for override properties for Objective-C compatibility, to mimic nil values in Swift

Note: This PR only creates the new properties; the logic to apply the overrides will follow in another PR.

Review checklist

• Feature or bugfix MUST have appropriate tests (unit, integration)
• Make sure each commit and the PR mention the Issue number or JIRA reference
• Add CHANGELOG entry for user facing changes

[datadog-datadog-prod-us1]

Datadog Report

Branch report: RUM-6224-create-overrides
Commit report: e0e5b6b
Test service: dd-sdk-ios

✅ 0 Failed, 3478 Passed, 0 Skipped, 3m 43.5s Total Time
🔻 Test Sessions change in coverage: 7 decreased, 3 increased, 4 no change

🔻 Code Coverage Decreases vs Default Branch (7)

This report shows up to 5 code coverage decreases.

• test DatadogInternalTests iOS 79.33% (-0.16%) - Details
• test DatadogTraceTests iOS 54.02% (-0.15%) - Details
• test DatadogLogsTests iOS 47.65% (-0.13%) - Details
• test DatadogWebViewTrackingTests iOS 18.51% (-0.07%) - Details
• test DatadogRUMTests iOS 81.04% (-0.07%) - Details