Masterbar Item: Do not pass component-specific prop to HTML elements

[zaguiini]

Fixes #109896 (comment).

Proposed Changes

Adds an extra asProps prop that is only filled if the user is passing a custom component through the as prop.

Testing Instructions

Enter /home/%s where %s is a site that has never been launched.

• Verify you don't see the console warning anymore.
• Verify you see the launch button.
• Verify you can click the launch button and the loading state still applies.

[github-actions]

Calypso Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-175385

Jetpack Cloud Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-175385&env=jetpack

Automattic for Agencies Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-175385&env=a8c-for-agencies

Dashboard Live (dotcom) (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-175385&env=dashboard

Dashboard Live (CIAB) (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-175385&env=dashboard-ciab

[matticbot]

This PR modifies the release build for the following Calypso Apps:

For info about this notification, see here: PCYsg-OT6-p2

• help-center
• notifications
• wpcom-block-editor

To test WordPress.com changes, run install-plugin.sh $pluginSlug fix/masterbar-unknown-is-busy-prop on your sandbox.