[VideoPress] Update onboard dialogues w/a link to add a license key


Task:
- Add a link: "Already have an existing plan or license key? Click here to get started" at the top of right corner in the VideoPress pricing table.

Flow after pressing the link:

Start by locating the VideoPress pricing table and onboarding dialogue components in the repository, then trace the action triggered by the new license-key link. Confirm the existing-plan flow shown in the attached design and verify that the link appears in the pricing table and reaches the intended onboarding step.

Written by the indexing model from the issue text.