feat: add support of [formnovalidate] in Abide

[SassNinja]

Description

This PR adds formnovalidate support to Abide. Precisely it checks for [type="submit"][formnovalidate] and disables the whole validation if clicked (emulates the native behavior https://www.w3schools.com/tags/att_input_formnovalidate.asp)
In the course of this I've added the method enableValidation that provides an easy way to enable/disable the validation.

• Closes abide: provide ability bypass validation on certain submit actions #11426

Types of changes

• Documentation
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (anything that would change an existing functionality)
• Maintenance (refactor, code cleaning, development tools...)

Checklist

• I have read and follow the CONTRIBUTING.md document.
• The pull request title and template are correctly filled.
• The pull request targets the right branch (develop or develop-v...).
• My commits are correctly titled and contain all relevant information.
• I have updated the documentation accordingly to my changes (if relevant).
• I have added tests to cover my changes (if relevant).

[ncoden]

Hi @SassNinja 👋,

Thank you for the pull request!
I have some remarks though regarding of the implementation.

[SassNinja]

@ncoden thanks for your review!

I've commented each of your remarks.
When using the feature in the test/visual/abide/text.html it behaves as I would expect.

[ncoden]

@SassNinja Could you add unit tests after we agreed on the expected behavior of the form at #11613 (review) ? 😄

the code has changes in the meantime

[kball]

Broadly looking good - a couple quick notes/questions but I don't think they block merging.

[joeworkman]

This pull request has been mentioned on Foundation Open Source Community. There might be relevant details there:

https://foundation.discourse.group/t/foundation-for-sites-v6-6-0-is-here-farout/30/1