The Search field at the top of the page and the Filter field on the New

Review Request page both had their own visual alignment and spacing

issues, in part due to altered styling in Ink and bad browser defaults.
The styling for rb-c-search-field now uses a more appropriate font

size for the FontAwesome-based icon, and a more appropriate spacing

between it and the text.
The issues in the Filter field were due to the lack of a type=

attribute, and the lack of default styling for an <input> without

type=. As fixing this globally for all type-less inputs would alter

precedence rules for other styles, I've opted not to touch those for

now. Instead, we now set the Filter field to type="search" explicitly.

Tested in light and dark modes for both of these fields.