Add ability to assert metadata properties on input dataset parameters

[bernt-matthias]

revive #3159 from @jmchilton (anno 2016 .. just a little bit more than crazy 10K PRs/issues in between :))

Changed the name for the validator .. dataset prefix might be good for comparability.

Not sure if one could / should generalize / reuse dataset_metadata_in_range (which considers only numbers at the moment).

ping @bgruening

Side note: I would find this super userful to check for column names, but tabular does not set them .. still downstream tools could and et voila it can be used :).

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[jmchilton]

Maybe metadata_equal for consistency with the above type?

What about stronger typing. I feel like I've been heading this way with tool stuff... if value is used treat it as a string and use a value_json attribute to json.load the value for a typed comparison.

I would make these two changes but you write more tools - if you prefer the way you have it here that is totally fine with me.

[bernt-matthias]

Maybe metadata_equal for consistency with the above type?

Hmm. We also have dataset_metadata_... maybe we can simplify/unify all this by adding a few aliases and name all of them metadata_...?

What about stronger typing. I feel like I've been heading this way with tool stuff... if value is used treat it as a string and use a value_json attribute to json.load the value for a typed comparison.

value_json is a great idea. I vaguely remembered that I have seen something like this but was not sure. I will add it.

I would make these two changes but you write more tools - if you prefer the way you have it here that is totally fine with me.

Thanks for the feedback. Give me a moment :)

[bernt-matthias]

While thinking about this I would suggest to stick with dataset_metadata_equal: All the user (ie tool developer) facing validators are prefixed with dataset_metadata_. The metadata validator is unlikely to be used by tool developers (its automatically added to each data parameter). So maybe this is an acceptable level of inconsistency...

[mvdbeek]

This needs a pass of black.

[bernt-matthias]

Good to go?

[github-actions]

This PR was merged without a "kind/" label, please correct.

[nsoranzo]

I'm late, but maybe MetadataEqualValidator instead of MetadataEqualsValidator for consistency?

[bernt-matthias]

Not to late #16489 :)

Thanks!