Add check/fix workflows for YAML files

[greenc-FNAL]

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[knoepfel]

@greenc-FNAL, the number of checks has gotten very large. Why do we need a YAML check? The action will not run if there's a YAML error, right? Which seems like a chicken-and-egg problem.

[greenc-FNAL]

Specifically for syntax errors in workflows, yes. It also enforces the usual style bits, like line length, unwanted trailing whitespace and indentation consistency.

There are several non-workflow YAML files in the repository rn (tool configurations), but I exepct there will be Phlex configs eventually, also.

These single language checks are quite fast (<10s) as long as we don't need a Phlex build environment to run them