Schema URL support Resource + api getTracer

[ericmustin]

in addition to the API updates here: open-telemetry/opentelemetry-js-api#125

OTEP-152 also defines a separate schema_url for resources as well as adds new merge behavior, https://github.com/open-telemetry/opentelemetry-specification/blob/49c2f56f3c0468ceb2b69518bcadadd96e0a5a8b/specification/resource/sdk.md#create

Just adding this issue to determine whether this is being worked on at the moment? Python and Go have implementations for reference, fwiw.

[github-actions]

This issue is stale because it has been open 60 days with no activity. Remove stale label or comment or this will be closed in 14 days.

[dyladan]

Marking as never stale since this affects the API and is required by the spec.