code quality: add PHPStan array shape for ability $properties

[justlevine]

What

This PR adds array shapes for the $properties array used by

• wp_register_ability()
• WP_Abilities_Registry::register()
• WP_Ability::__construct()

Why

To ensure both we and consumers are using the correct array shapes.

Additional Notes

• Generics are not used e.g. to hint the schema/meta shapes. Until core supports generics, that extra level of DX would fall to a 3rd party library like php-stubs/wordpress-stubs.
• As a result of the array shapes we could in theory make the param less verbose, but human contribs might not be familiar with the syntax, so I left it out.

[justlevine]

I don't have perms to rerun the failing CI, but since it's for WP6.7 which we're removing in #18 🤷

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (trunk@a749d71). Learn more about missing BASE report.

Additional details and impacted files

@@           Coverage Diff            @@
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  Coverage         ?   90.66%           
  Complexity       ?       99           
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  Files            ?        7           
  Lines            ?      557           
  Branches         ?        0           
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  Hits             ?      505           
  Misses           ?       52           
  Partials         ?        0           

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[gziolo]

That's very useful addition 👍🏻

[gziolo]

Everything else gets ignored, do we need to list it?

[justlevine]

That's exaclty why it's here - this is the long-overdue syntax for partially sealed arrays.

Otherwise if users don't clean up their arrays (or more "justifiable" real world scenario: if extensions hook in their own custom args) they'll get errors about unsupported array values, when it doesn't matter because we only keep the ones we need.

[gziolo]

I don’t think it adds any value at the moment because it’s impossible to successfully pass more settings. It’ll rather change in the future when we add WP hooks.