Add cornerActions to Sidebar

[thure]

This PR introduces cornerActions which developers can use to add upward or backward navigation to Sidebar.

To do

• [x] The text item button should invoke a tooltip, either always or just if it's overflowing
• [x] Try a three-dots menu between home and and the text item in the 3+ case
• [x] Use the home_more icon if not using the three-dots menu variant in the 3+ case
• [x] Sidebar items must emit actions

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: d7e43eec4d8a36db5f673942c98dd120352dbcc3

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

| Name | Type | | -------------------------- | ----- | | @fluent-blocks/react | Minor | | @fluent-blocks/schemas | Minor | | @fluent-blocks/basic-icons | Patch |

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