Refactor javascript behaviors directory

What does this MR do?

Resolves eslint violations, removes IIFEs, refactors to ES module syntax, and consolidates import statements to a single index file.

Are there points in the code the reviewer needs to double check?

No previously working functionality relating to behaviors should stop working.

Why was this MR needed?

General technical debt elimination.

Screenshots (if relevant)

n/a

Does this MR meet the acceptance criteria?

• [ ] Changelog entry added, if necessary
• [ ] Documentation created/updated
• [ ] API support added
• Tests
  • [ ] Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

marked the task All builds are passing as completed

assigned to @alfredo1

@alfredo1 can you review this?

@mikegreiling should this go in 9.1?

I don't think it matters if it makes it into 9.1 or not. It's just tech debt. Feel free to wait for monday to merge.

changed milestone to %9.1

merged

mentioned in commit 01adf920

LGTM. I've set it 9.1