Converts NavDrawer, NavDrawerGroup, and NavDrawerFlyout to TypeScript

[dimitropoulos]

Summary

closes #2658
closes #2772

I decided it would be most scientific (and interesting!) to do a clean-room implementation (at first, anyway) from the original PR #2772. Upon taking a look, a lot of the things are the same, but many are different.

As always, I tried very hard to stick to the components in question to avoid scope creep ("Rome wasn't built in a day"-kinda thing), as well as notating every single instance where I feel that there's potential for logical changes :)

Checklist

• Check against all themes for compatibility in both light and dark modes
• Checked in mobile
• Checked in IE11 and Firefox
• Props have proper autodocs (could use a double check on this!)
• Added documentation examples
• Added or updated jest tests
• Checked for breaking changes and labeled appropriately
• Checked for accessibility including keyboard-only and screenreader modes
• A changelog entry exists and is marked appropriately

[kibanamachine]

Since this is a community submitted pull request, a Jenkins build has not been kicked off automatically. Can an Elastic organization member please verify the contents of this patch and then kick off a build manually?

[thompsongl]

jenkins test this

[kibanamachine]

Preview documentation changes for this PR: https://eui.elastic.co/pr_3268/

[thompsongl]

Thank you, @dimitropoulos!

Nice work, as always, so I think this is close.

[dimitropoulos]

thanks for the swift review @thompsongl! I think it's pretty much ready to go now 🐎

[thompsongl]

Just a couple small things and the merge conflict to fix.

Confirmed that these changes work with very minor upates to Kibana

[thompsongl]

jenkins test this

[kibanamachine]

Preview documentation changes for this PR: https://eui.elastic.co/pr_3268/

[thompsongl]

LGTM!

Built locally and tested the output in Kibana (type check script and manual smoke test)

[tushar22-tg]

@dimitropoulos are you a GSoC applicant?

[dimitropoulos]

@dimitropoulos are you a GSoC applicant?

@tushar22-tg Google Summer of Code? no, just a friendly neighborhood open source contributor :)