Set up CI to lint workflows with action-validator

[Johennes]

This is the equivalent of element-hq/element-web#26621 applied to this repository

This, unfortunately, required renaming the release-action workflow because its name threw off the validator.

For: matrix-org/matrix-react-sdk#11930
For: element-hq/element-web#26641
For: element-hq/element-desktop#1347

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This change is marked as an internal change (Task), so will not be included in the changelog.

[t3chguy]

could we safely rename and do you have any suggestions for a better name?

We could but it'd have to be replicated onto the 3 repos calling this workflow

[Johennes]

We could but it'd have to be replicated onto the 3 repos calling this workflow

I assume this is safe to do outside of release days? How about renaming it into release-executor.yml? I'm blanking on good names.

[t3chguy]

It should be but beware sod's law