ROX-16317: Extract a reusable data plane deployment workflow.

[porridge]

Description

Another copy of the rollout workflow (for the PR check) would be too much.
So I'm extracting the common code into a reusable workflow.

One unclear thing is whether we should be setting concurrency in the reusable or in the caller workflow.
One data point is that the linter complained about using ${{ inputs... }} in the reusable workflow name, but does not complain when I use it in the concurrency field, so I'm hopeful it will work as intended.

Also adding a GHA linter workflow while at it, stolen from stackrox/stackrox but using latest rather than a pinned version, and running only when files in the .github dir change.

Checklist (Definition of Done)

• Unit and integration tests added
• Added test description under Test manual
• Documentation added if necessary (i.e. changes to dev setup, test execution, ...)
• CI and all relevant tests are passing
• Add the ticket number to the PR title if available, i.e. ROX-12345: ...
• Discussed security and business related topics privately. Will move any security and business related topics that arise to private communication channel.

Test manual

Ran actionlint.

[kovayur]

Nice refactoring 👍. It would be even nicer to see the github actions linter as a pre-commit hook, but not critical.

[porridge]

PTAL @kovayur

[porridge]

Executable `actionlint` not found

Ha, it's not as easy as I thought. Should I revert the latest commit, or do we want to fetch the tool in the precommit action? WDYT @kovayur ?

[openshift-ci]

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[kovayur]

/retest