Handle highlight with mouse events only

[dopatraman]

Goal:
The goal of this PR is to use javascript mouse events to highlight active elements in the emoji dropdown.

Summary:
Right now, the first item of the emoji dropdown stays highlighted even when selecting other elements. The reason for that is that the current logic does not deactivate the first element when the dropdown is first shown. This PR deactivates all elements on every mouse movement.

[dopatraman]

pinging @yuku for visibility.

[yuku]

LGTM!

[aki77]

This PR has broken the fix for #323.
This is a weird behavior when the dropdown is made scrollable.

If you look at the behavior of GitHub's Mention input, for example, the behavior in v0.1.6 is more natural.

[aki77]

@yuku @dopatraman

What do you think about the above behavior?

[yuku]

This is a weird behavior when the dropdown is made scrollable.

Thanks. I could reproduce the behavior:

[yuku]

Because of my lack of interest on the project, I'd approved this PR by just watching the fancy gif in the PR description.

Now I had closer look at the patch and found some issues in that. (For example, I'd like to avoid using any whenever possible. I should have added a test case to confirm that. Its my bad 😞 )

So I'm going to revert this PR. Sorry for my inconsistency.

[aki77]

Thanks! 🙏