[Replay] Refactors and Nice-to-have Improvements

[Lms24]

Problem Statement

With #5326 completed, we found many areas of improvement in the Replay integration. These tasks are not strictly related anymore to the migration. We should sit down and discuss time budget, prioritize the tasks and extract them to separate issues.

Progress

• [Replay] Remove lodash.debounce dependency #6553
• Make bundle size optimizations
  • ref: Avoid optional chaining & add eslint rule #6777
  • ref(tracing): Remove nullish coalescing operator and add eslint rule #6783
  • Move Class field initializations to constructor
• Convert Replay class to functions
  • [Replay] Split up main index.ts for better composability #6406
• [Replay] Align Replay event metadata #6366
• Improve worker build for replays #6371
• [Replay] Move rrweb-specific configuration into recordingOptions #6390
• Generate "full" bundles
  • browser + tracing +replay
  • browser + replay (NOT DONE - maybe later??)
• Rename interfaces (ISomething doesn't conform with our conventions)
• Figure out what to do with demo (maybe move to E2E tests?)

Won't do

• Can we entirely get rid of the keepAlive flag in our fetch transport? This flag is causing issues for users (Sentry requests are pending indefinitely #6049) but removing it might cause more replay segment loss.

[smeubank]

tracking with own issues in the checklist