[opentelemetry-resourcedetector-gcp] Fix directory structure and version number

[DylanRussell]

Description

Moved source package from src/opentelemetry/resource/detector/gcp/ to src/opentelemetry/resourcedetector/gcp_resource_detector/.

Updated package namespace from opentelemetry.resource.detector.gcp to opentelemetry.resourcedetector.gcp_resource_detector.

This matches the directory structure and namespace in https://github.com/GoogleCloudPlatform/opentelemetry-operations-python/tree/main/opentelemetry-resourcedetector-gcp , which we want to do to avoid breaking people..

I didn't mean to change the directory structure in the first place. My agent did it and I didn't notice..

If it's important to match the directory structure used in this repo we could also leave it as it is now (revert this change), but add a compatibility shim (re-import GoogleCloudResourceDetector) under the existing path: src/opentelemetry/resourcedetector/gcp_resource_detector/ since GoogleCloudResourceDetector is the only public object in this package.

Let me know what y'all think...

Also I've fixed the version number in this PR (added the a0 suffix back) so the next release will be 1.14.0a0 -- this matches how we were doing it in the old repo..

Fixes #4855

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Unit tests

Does This PR Require a Core Repo Change?

• No.

Checklist:

See contributing.md for styleguide, changelog guidelines, and more.

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[tammy-baylis-swi]

Good to change it back in this PR. Can discuss namespacing and major release later