[4.0] Cleanup formvalidation uses

[wilsonge]

Partial Pull Request for Issue #25490 .

Summary of Changes

• Adds the class form-validate to various forms so that they are correctly used by the validator.
• Adds the formvalidator javascript to the installer where we had the classes but not the JS
• Removes the data-cancel-task attribute from com_config where we now no longer use core mvc and it follows the "normal" task pattern

Basically every form using the formvalidator behaviour is now associated with a form containing the form-validate class. (The password field additionally includes the behaviour without the class but that is outside the scope of the PR as the JS has a hard dependency)

Testing Instructions

Ensure form validation in forms continues to work especially in the forms affected in this PR

Documentation Changes Required

None

[chmst]

I have tested this item ✅ successfully on 9d3b8f5

All forms work as before, so it is successful test.
Validation itself does not work for numbers but this is not in scope of this PR.

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[jwaisner]

I have tested this item ✅ successfully on 9d3b8f5

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/28352.}

[jwaisner]

RTC

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[wilsonge]

Cheers guys