[Integration tests]: manually get the current commit for the action when bootstrapping the project.

[IfSentient]

This PR does two things:

• Moves testing to a reusable workflow which is now shared between the main, pr, and release workflows.
• Updates the integration tests to use the version of the grafana-app-sdk that matches the code the action is being run against (using a replace directive in the go.mod, as using GITHUB_SHA doesn't cooperate with go get in PR builds).

Currently, the branch protection settings for main require that an action named test complete successfully to merge (which no longer exists the same way, so this blocks indefinitely), once this PR is approved I will update the branch protection settings to require test / unit-test, test / integration-test, and test / build instead, then merge this PR so other PR's will need to merge in from main to get correct testing.

[radiohead]

@IfSentient Looks like using git to get commit rev won't work, but we could get that info from the env vars – https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/store-information-in-variables#default-environment-variables.

IIUC GITHUB_SHA should fit the bill.

[IfSentient]

@IfSentient Looks like using git to get commit rev won't work, but we could get that info from the env vars – https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/store-information-in-variables#default-environment-variables.

IIUC GITHUB_SHA should fit the bill.

I tried that before, and I get the error

go: github.com/grafana/grafana-app-sdk@9bb57268ee194cd7cfa69a892ec20d1293134cef: invalid version: unknown revision 9bb57268ee194cd7cfa69a892ec20d1293134cef

It looks like 9bb57268ee194cd7cfa69a892ec20d1293134cef exists, but is some kind of fake commit that is the totality of the PR instead of being a commit in the branch or in main, which I suspect is why go get is having problems.