EuiFieldPassword: converted to Typescript

[ffknob]

Summary

Closes #2650
Converted EuiFieldPassword to Typescript.

Checklist

• Check against all themes for compatability in both light and dark modes
• Checked in mobile
• Checked in IE11 and Firefox
• Props have proper autodocs
• 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

[elasticmachine]

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]

Thanks, @ffknob!

Also, you can remove the TS reference in src/components/form/index.d.ts line 3:
/// <reference path="./field_password/index.d.ts" />
and then delete the ./field_password/index.d.ts file as it is no longer needed

[thompsongl]

jenkins test this