Plugin-E2E: Add version resolver action

[sunker]

What this PR does / why we need it:

This PR adds an Github Action action that has the purpose of resolving what Grafana versions to target in the E2E tests. The output of the action is a json array of Grafana minor versions that can be used to specify a version matrix in the next workflow job. See this example.

Currently, the actions support two modes:

plugin-grafana-dependency (default)
The will return all minor versions of Grafana since the version that was specified as grafanaDependency in the plugin.json. (does not work for this repo since it's not a plugin).

version-support-policy
This will resolve versions according to the min support policy defined in this doc. TLDR; all minors for the current major version and the last minor of the previous major version.

If a plugin author requires more flexibility, they can ofc define their own matrix.

At some point (when it's more stable) we probably want to move this action to its own repo and tag a release. Maybe also rewrite using Typescript.

Which issue(s) this PR fixes:

Fixes #
Part of #576

Special notes for your reviewer:
For now I'm just creating a bundle using the following command and committing it.

npx ncc build ./index.js -o output

When the action is moved to its own repo, we can look at better alternatives for this.

[github-actions]

Hello! 👋 This repository uses Auto for releasing packages using PR labels.

✨ This PR can be merged. It will not be considered when calculating future versions of the npm packages and will not appear in the changelogs.

[sunker]

Need to uncomment before merging

[jackw]

At some point (when it's more stable) we probably want to move this action to its own repo and tag a release. Maybe also rewrite using Typescript.

I was going to suggest this could be moved to the plugin-actions repo.

[sunker]

At some point (when it's more stable) we probably want to move this action to its own repo and tag a release. Maybe also rewrite using Typescript.

I was going to suggest this could be moved to the plugin-actions repo.

Ah sweet, didn't know we had that repo. In that case I'm closing this PR. Will open a new one in plugin-actions shortly.