🖍 Add preliminary styles for amp-autocomplete

[andrewwatterson]

Builds on @caroqliu's work on amp-autocomplete - this adds some styling to the autocomplete input and results list.

Very much a work in progress.

[andrewwatterson]

@cvializ @caroqliu - This has been as "ready" as any other pre-release autocomplete code for awhile, though it may be incomplete.

The only thing we might want to change before merge is that I had to manually reset a bunch of the i-amphtml-fill-content styles that were applied to i-amphtml-autocomplete-results. Did we ever investigate whether we can avoid adding the fill-content styles in the first place?

[cvializ]

Yes, @caroqliu investigated and was able to remove the applyFillContent call, so those styles shouldn't be needed. You can merge this branch with master and see those changes in your PR so you can remove the style overrides.

[andrewwatterson]

Arrite @cvializ I took those styles out. Assuming it passes checks, should be good to merge.

[cvializ]

LGTM