docs(toolbar,menuBar): add md-toolbar-filler examples

[Splaktar]

PR Checklist

Please check that your PR fulfills the following requirements:

• The commit message follows our guidelines
• 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
[x] Documentation content changes
[ ] Infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

The md-toolbar-filler examples for md-menu-bar were removed because the icons were broken.
There are no examples of using md-toolbar-filler with md-toolbar.

This was found with the review of #11258.

Issue Number:
Relates to #11258

What is the new behavior?

Re-added the md-toolbar-filler examples for md-menu-bar with fixed icons.
Added a md-toolbar-filler example to the Toolbar Basic Demo.
removed some unneeded icons (they are already in docs/app/img/icons/.
register the icon sets in the docs app
fix strange absolute styling alignment issue

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

N/A

[Splaktar]

MenuBar:

Toolbar: