RUMM-2171 Single Storage Queue

[maxep]

What and why?

Use single storage queue.

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

Custom CI job configuration (optional)

• Run unit tests
• Run integration tests
• Run smoke tests

[ncreated]

Looks good 👌💯. I left one feedback on potential small improvement in tests.

[ncreated]

There is one potential step we could look into in this PR. Now, by having an explicit access to this r/w queue we can simplify this test:

dd-sdk-ios/Tests/DatadogTests/Datadog/DatadogTests.swift

Lines 445 to 453 in 94819c0

	// On SDK init, underlying `ConsentAwareDataWriter` performs data migration for each feature, which includes
	// data removal in `unauthorised` (`.pending`) directory. To not cause test flakiness, we must ensure that
	// mock data is written only after this operation completes - otherwise, migration may delete mocked files.
	let loggingWriter = try XCTUnwrap(logging?.storage.writer as? ConsentAwareDataWriter)
	let tracingWriter = try XCTUnwrap(tracing?.storage.writer as? ConsentAwareDataWriter)
	let rumWriter = try XCTUnwrap(rum?.storage.writer as? ConsentAwareDataWriter)
	loggingWriter.queue.sync {}
	tracingWriter.queue.sync {}
	rumWriter.queue.sync {}

We .sync {} on each Feature's queue, but now it can be single core.readWriteQueue.sync {}.

[maxep]

Good catch!