Chore/4112 dropdownitem icon

[evwilkin]

What: Closes #4112

This PR updates the DropdownItem component to take an icon prop to mirror the pattern used in #4038. This change removes the need for DropdownItemIcon component, that component is removed completely.

Breaking changes

• Dropdown:
  • Remove DropdownItemIcon in favor of <DropdownItem icon={} />
  • Remove variant prop from DropdownItem. If you were using variant="icon" before, use the new icon prop instead.

[patternfly-build]

PF4 preview: https://patternfly-react-pr-4147.surge.sh
A11y report: https://patternfly-react-pr-4147-coverage.surge.sh

[jenny-s51]

Great update! LGTM 🙂

[redallen]

Can you add this to your PR body's text to something like this?

## Breaking changes
- **Dropdown:**
  - Remove DropdownItemIcon in favor of <DropdownItem icon={<Icon />} />
  - Remove variant prop from DropdownItem. If you were using variant="icon" before, use the new icon prop instead.

[redallen]

Update the PR body and then next step is to write a codemod :)

[patternfly-build]

Your changes have been released in:

• @patternfly/react-catalog-view-extension@4.2.11
• @patternfly/react-core@4.9.5
• @patternfly/react-docs@5.2.15
• @patternfly/react-inline-edit-extension@4.3.11
• demo-app-ts@4.6.8
• @patternfly/react-integration@4.6.3
• @patternfly/react-table@4.3.11
• @patternfly/react-topology@4.2.11
• @patternfly/react-virtualized-extension@4.2.11

Thanks for your contribution! 🎉