feat(router): expose resolved route title

[EmmanuelRoux]

fixes #46825

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/angular/angular/blob/main/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• angular.io application / infrastructure changes
• Other... Please describe:

What is the current behavior?

Issue Number: #46825

What is the new behavior?

Since Angular 14, router has a new mechanism to update page title from route config. The route can either be a static string or resolved in the same way as resolve data.

But the resolved route title is not exposed and inaccessible from client application (it seems the title is actually stored in the resolved Data, but using a private Symbol so it can't be accessed properly).

This PR adds a new title property on ActivatedRoute and ActivatedRouteSnapshot.

Does this PR introduce a breaking change?

• Yes
• No

Other information

[atscott]

LGTM for the changes. Before we merge, could you please squash the commits into one?

[atscott]

reviewed-for: public-api

[AndrewKushnir]

Reviewed-for: public-api

[jessicajaniuk]

reviewed-for: public-api

[atscott]

caretaker note: This will require patching cl/462221001 when syncing.

[atscott]

green TGP with patches

[atscott]

merge assistance:

• This will require patching cl/462221001 when syncing.
• TGP was green with the local patch but it would be a good idea to merge and sync this on its own

[pkozlowski-opensource]

This PR was merged into the repository by commit 10289f1.

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