normalize is no longer part of BS

Change 'has no affect' to 'has no effect' in Modal documentation

Add `utilities/flex` to the dedicated grid Sass bundle so folks can take advantage of the utilities for basic flex alignment

Add aria-label to docs search field

Fixes #21560. Pretty sure this wasn't intentional, so should be fine to remove.

Fixes #21699

* rename order utilities to intended class names

* Documentation fixes.

The actual available size of the navbar toggler icon is 30px, but the
SVG uses a 32 unit grid. This commit uses a 30 unit grid and updates
icon accordingly.

- Correctly places the _custom.scss file first in the other two buids.
- Also removes the clearfix mixin from the grid build because flexbox yo.

* Remove most of custom cursor: pointer; implementations

* turns out that's not so much of a thing

The actual navbar height is 3.5rem.

Header will now display in the Contents section.

Update Mix and match section with correct responsive classes
for stacking cols.

* Get this party started by removing mention of Normalize.css

* Nuke the old comment, consolidate to a single line and number as appropriate

* Bring over styles for HTML element from Normalize to Reboot

* Move margin override for body element from Normalize to Reboot

* Drop the block reset for HTML5 elements in IE9- from Normalize given we dropped IE9 support

* Building on previous commit, do the same thing for figure, figcaption, and main

* Remove IE9- display from Normalize given our browser support

* Drop IE8 figure margin because we're IE10+

* No need for the h1 overrides because we reset these font and margin styles anyway in _type.scss already

* Drop Safari 6 b and strong normalization because we're Safari 8+

* Remove mark styles for IE9- from Normalize

* Remove old iOS audio fixes from Normalize

* Remove IE9- display for progress from Normalize

* Remove more IE9- rules from Normalize

* One more IE9- display removal for canvas element

* Move pre overrides from Normalize to Reboot

* Move over some link resets to Reboot, drop others

- Move over background-color and text-decoration
- Drop focus outline change given it affects the offset on hover of
focused links

* Move over more code element resets, consolidate with pre overrides, too

* Move over sub and sup wholesale

* Move over img normalization to Reboot

* Move over SVG override too

* - Drop dupe hidden, but add comment for it
- Move over template
- Move over summary

* Remove bulk of @viewport comment

* edit down that code comment

* consolidate html-based normalizations

* update comments

* Consolidate abbr styles

* move over more type elements

* move over hr changes

* move over form controls and more

* move over button resets

* move over firefox button changes

* move over search changes and more

* we nuke all these styles for fieldsets anyway, so outright remove them

* no need for those, we override them

* move over legend, fieldset, progress

* line break

* delete normalize file

* linting

* update comment

* clarify docs mentions of normalize and reboot

* remove normalize excludes from linter

* remove normalize excludes from cli task

* linting

* callout license since we forked part of normalize

* Improve comments, move table background reset to .table class instead of in reboot

* trailing space