Add context propagation type to generateUUID method

[jhssilva]

What does this PR do?

• Improves the method generateUUID by generating UUIDs for different Propagator type

Motivation

The current generateUUID method is incomplete as it doesn't generates correctly spans for RUM, or trace context propragation.

Additional Notes

Two approaches were consider:

• Exposing the toString method allowing users to define the TracingIdFormat
• Improve the generateUUID allowing users to choose the traceContext

Context
RUM resources requires (context):

• TraceId: TracingIdFormat.paddedHex
• SpanId: TracingIdFormat.decimal

While the Datadog Trace Context propagation requires (context):

• TraceId: TracingIdFormat.lowDecimal
• SpanId: TracingIdFormat.decimal

This creates a discrepancy when generating UUIDs for inclusion in headers and resources, particularly to circumvent cases where SSL pinning is used or when dealing with libraries not supported by the SDK.

Tests

For the tests it was mimic from the following code

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]

@jhssilva Amazing 🚀 thank you for the contribution!

I have implemented your changes in #793, since I wanted to encapsulate the logic in a separate class, since IMO it was becoming a bit too complex to keep it in DdRum.ts.

The idea is to return an object on which devs can call:

• forResource() to format it for resources
• forContextPropagation(propagationType) to format it for the desired context propagation type
• toString(tracingIdFormat) to format it to a custom format (potentially covering future use cases we are not aware of)
• type to verify the generated UUID type
• id to access the UUID in raw format (big integer)

[marco-saia-datadog]

Closing this PR as it is been replaced by #793