[canvas] Restore Workpad Title/button to Home; fix mounting behavior

[clintandrewhall]

Summary

#102446 removed the Canvas title in the lower-left, as it opened a Workpad dialog that we removed, and the breadcrumb navigation provided the same functionality. Thinking back on it, it made sense to restore that button, but just have it also link home.

This PR also fixes an issue where the initial load of Workpads fires too many times, (as the onMount hook doesn't fire only once).

[elasticmachine]

Pinging @elastic/kibana-presentation (Team:Presentation)

[mdefazio]

LGTM

[cqliu1]

It feels a little odd to redirect the user back to the Canvas home page when they click on the workpad title on the bottom left. For a user new to Canvas, I think I'd be a little confused why clicking on the title in the bottom left backed me out of the workpad, since that's not what the workpad title breadcrumb does when you click on it (which just reloads the same workpad).

I'd be in favor of leaving it removed or making it static text, and have the users only navigate via the breadcrumbs. I don't believe there's a button to redirect you back to the dashboard listing when you're in a dashboard besides the breadcrumbs, and I think it'd be fine to expect the same in Canvas.

On that note looking in Dashboard, it looks like the dashboard title breadcrumb isn't clickable, so we should probably follow the same pattern and make the workpad title breadcrumb just static text.

The rest of the code LGTM 👍

[clintandrewhall]

@cqliu1 I agree, and made the changes you suggested. Thanks!

[clintandrewhall]

jenkins test this

[clintandrewhall]

@elasticmachine merge upstream

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 0fcd518
• Storybooks Preview
• Documentation Changes

Metrics [docs]

Module Count

Fewer modules leads to a faster build time

id	before	after	diff
canvas	1044	1042	-2

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
canvas	1.2MB	1.2MB	+349.0B

History

• 💔 Build #135426 failed 2f366b4
• 💚 Build #135377 succeeded 2f366b4
• 💚 Build #134920 succeeded b09c7d7
• 💔 Build #134912 failed 5c83b35

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

[kibanamachine]

💚 Backport successful

Status	Branch	Result
✅	7.x

This backport PR will be merged automatically after passing CI.