feat: add hold as a trigger event modifier

[81reap]

Description

Please describe what changes you made, and why you feel they are necessary. Make sure to include code examples, where applicable.

adds hold as a trigger event

Corresponding issue:

None, I wanted to create a hold-to-click interaction and realized how common of a pattern it is, so I decided to take a stab at upstreaming it into HTMX

old PR :: https://github.com/bigskysoftware/htmx/pull/3438

Testing

Please explain how you tested this change manually, and, if applicable, what new tests you added. If you're making a change to just the website, you can omit this section.

I tried to test as many edge cases as I could, if any reviewer comes up with more, I can try adding those too. :)

Checklist

• [y] I have read the contribution guidelines
• [y] I have targeted this PR against the correct branch (master for website changes, dev for source changes)
• [n] This is either a bugfix, a documentation update, or a new feature that has been explicitly approved via an issue
• [y] I ran the test suite locally (npm run test) and verified that it succeeded

[81reap]

I was recommended by latent3611 on the Discord server to make a sample extension as well

https://github.com/81reap/htmx-ext-hold