[RUM-9272] Add configurable time for classifying resources for TNS metric

[sbarrio]

What does this PR do?

This PR adds a new config property called initialResourceThreshold, which allows users to set the maximum time threshold (counting from view start, in seconds) inside of which a resource should be considered for the "Time to Network Settled" metric.

Motivation

Exposing custom TNS settings for clients.

Additional notes

RN config

iOS custom TimeBasedNetworkSettledPredicate set

Android custom initialResourceIdentifier set

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests
• Make sure you discussed the feature or bugfix with the maintaining team in an Issue
• Make sure each commit and the PR mention the Issue number (cf the CONTRIBUTING doc)
• If this PR is auto-generated, please make sure also to manually update the code related to the change

[marco-saia-datadog]

Looks good! My only suggestion is to add a few tests on the React Native layer as well.

[sbarrio]

Looks good! My only suggestion is to add a few tests on the React Native layer as well.

Agree, will do!

[marco-saia-datadog]

An iOS check is also failing:

❌ /Users/ec2-user/builds/JBp7x9hf6/0/DataDog/dd-sdk-reactnative/packages/core/ios/Tests/DdSdkTests.swift:1138:57: cannot find 'onThresholdLImitResource' in scope
        XCTAssertTrue(predicate.isInitialResource(from: onThresholdLImitResource))

[sbarrio]

An iOS check is also failing:

❌ /Users/ec2-user/builds/JBp7x9hf6/0/DataDog/dd-sdk-reactnative/packages/core/ios/Tests/DdSdkTests.swift:1138:57: cannot find 'onThresholdLImitResource' in scope
        XCTAssertTrue(predicate.isInitialResource(from: onThresholdLImitResource))

Ah, of course, I renamed it but didn't change the test. On it!

[marco-saia-datadog]

LGTM 🚀