Ensures the example viewer header displays correctly by keeping the "Show code"
button aligned to the right and preventing metadata text from wrapping.
Improves layout consistency across documentation examples.
The example viewer has some `::ng-deep` styles that are used to reset global styles that leak into the live examples. It works by applying a style like `.docs-example-viewer-preview * {all: revert;}`.
The problem with this is that depending on when the first example is rendered, the styles will be lower or higher in the cascade, thus making the reset unreliable. Furthermore, it can affect structural styles from the CDK which intentionally have low specificity.
These changes move the resets into the global stylesheet to make them more predictable.
To increase the ease of development we are moving @angular/docs into the adev directory within this repo. While
we are doing this to improve our development experience in the short term, efforts are also in place
to maintain a division between this @angular/docs (shared) code and adev itself, so that it can be extracted
back out in the future when components is ready to leverage it as well.
PR Close#57132
