Add http.route tags for API Gateway

[nhulston]

What does this PR do?

Adds http.route tags for Lambdas that were triggered by API Gateway.

• For APIGW v1, we set the route to the resource
• For APIGW v2, we set the route to the routeKey

Motivation

These tags are used by API Catalog
https://datadoghq.atlassian.net/browse/SVLS-5779

A similar PR for universal instrumentation (Java, .NET, Golang) is already done: DataDog/datadog-agent@315c38f

See DataDog/datadog-lambda-python#524 for Python changes

Testing Guidelines

Manual tests; updated unit tests and snapshots

Additional Notes

Types of Changes

• Bug fix
• New feature
• Breaking change
• Misc (docs, refactoring, dependency upgrade, etc.)

Check all that apply

• This PR's description is comprehensive
• This PR contains breaking changes that are documented in the description
• This PR introduces new APIs or parameters that are documented and unlikely to change in the foreseeable future
• This PR impacts documentation, and it has been updated (or a ticket has been logged)
• This PR's changes are covered by the automated tests
• This PR collects user input/sensitive content into Datadog
• This PR passes the integration tests (ask a Datadog member to run the tests)