Refactor TracePipeline

- Add LoadedFiles class to store loaded files/parsers and manage override policies.
- Add WinscopeErrorListener to notify load/parse errors.
- Make Trace objects immutable (never create uninitialized traces that need the timestamp type to be specified later).
- Build traces parsers from Traces object (instead of raw parsers).

Fix: b/308934313
Test: npm run test:presubmit
Change-Id: I69b141e7d5e8936d0f59b707d0f80aaaa90d35a8
27 files changed