[TypeScript]: EuiToggle, EuiButtonGroup, EuiButtonToggle, EuiFilterButton, EuiFilterGroup, EuiFilterSelectItem

[thompsongl]

Summary

• Converts EuiToggle to TypeScript ( drop in the bucket [META] TypeScript conversion of EUI #1557 )
• Adds type definitions for EuiButtonGroup and EuiButtonToggle ( resolves Missing TS defs: EuiButtonGroup, EuiButtonToggle #1566 )
• Adds type definitions for EuiFilterButton, EuiFilterGroup, and EuiFilterSelectItem ( resolves EuiFilterGroup / EuiFilterButton / EuiFilterSelectItem missing TypeScript definition #1492 🌊 🔵 )

Checklist

- [ ] This was checked in mobile
- [ ] This was checked in IE11
- [ ] This was checked in dark mode
- [ ] Any props added have proper autodocs
- [ ] Documentation examples were added

• A changelog entry exists and is marked appropriately

- [ ] This was checked for breaking changes and labeled appropriately

• Jest tests were updated or added to match the most common scenarios

- [ ] This was checked against keyboard-only and screenreader scenarios
- [ ] This required updates to Framer X components

[snide]

I did a functionality scan of the components listed. All work and display auto docs as I'd expect. I did not scan the code other than doing a brief check.

[chandlerprall]

Changes LGTM