feat(top-app-bar): migrate toolbar to top-app-bar

[CaerusKaru]

Bug, feature request, or proposal:

feature request

What is the expected behavior?

Toolbar should be migrated to top-bar, there should be no toolbar component

What is the current behavior?

Toolbar, but no top- or bottom-bar

What is the use-case or motivation for changing an existing behavior?

The spec has been updated to not include a toolbar, instead allowing for "App bars", both top- and bottom-.

Is there anything else we should know?

MDC is also doing this, and it is being tracked here

Tasks

• Scaffold empty classes, assets, demo, build config, etc.
• Stub existing component API
• Hook up MDC foundation and adapter
• Add remaining features on top of MDC implementation
• Test dark theme
• Test RTL
• Test with screen-readers
• Copy existing unit tests and ensure they all pass
• Copy existing e2e tests and ensure they all pass (if any)
• Verify SSR support in universal-app/
• Verify no size regression
• Create test harness
• Create schematics for migration
• Create user documentation

Additional notes

Breaking changes

Known issues & visual differences

[mhosman]

🤤🤤🤤🤤🤤

[Splaktar]

Related: MDC's mdc-top-app-bar

[Splaktar]

For reference, here's the merged PR for MDC's mdc-top-app-bar.

@mhosman that's a bottom-app-bar rather than top-app-bar. I've opened #16367 to track the creation of a mat-bottom-app-bar.