Snapshot: Show proper breadcrumb path

[ashharrison90]

What is this feature?

• moving to scenes regressed the breadcrumbs in dashboards
• updates the getDashboardUrl function to account for whether the dashboard is a snapshot or not
• adjusts the navModel in DashboardSceneRenderer to also check if the dashboard is a snapshot and set the section to Snapshots correctly

Why do we need this feature?

• show proper breadcrumb path when viewing a snapshot

Who is this feature for?

• anyone using snapshots

Which issue(s) does this PR fix?:

Fixes #96830

Special notes for your reviewer:

Please check that:

• It works as expected from a user's perspective.
• If this is a pre-GA feature, it is behind a feature toggle.
• The docs are updated, and if this is a notable improvement, it's added to our What's New doc.

[evictorero]

Great! Thanks for taking care of this, tested and looks good.
Probably not part of this PR but one thing to notice is this won't fix the unauthenticated view of a snapshot. Opening the same Snapshot in an incognito window will still display the Page not found in the breadcrumb.

[ashharrison90]

Great! Thanks for taking care of this, tested and looks good. Probably not part of this PR but one thing to notice is this won't fix the unauthenticated view of a snapshot. Opening the same Snapshot in an incognito window will still display the Page not found in the breadcrumb.

yep for sure, that's captured in #96988

it's more general than just snapshots anyway. it's a generic access problem of "what should we show if a user doesn't have permission to a certain resource"? right now we just show "Not found" which isn't great, but at least it isn't leaking any details that should be restricted 😅