Feature/ucsc 84/breadcrumb hero

[Vinsanity]

What does this do/fix?

• Adds a new block pattern for a page header hero with breadcrumbs.
• Adds two new templates for a page with no title. One with breadcrumbs support and one without.
• Leveraged existing breadcrumb functions and modified them to work with the new block pattern and templates.
• Added new variables and mixins to help with content width restrictions in blocks without width support.
• Added styles for the new block pattern.
• Updated styles for breadcrumbs.
• Fixed an error with the localization domain on the blocks.php file.

QA

Links to relevant issues

• Link to ticket
• Link to the screencast

Tests

Does this have tests?

• [ ] Yes
• [x] No, this doesn't need tests
• [ ] No, I need help figuring out how to write the tests.

[Herm71]

These build great on my machine. Approve!