Support three new filter types: checkbox, select and ternary select.
The ternary select tool is meant to support fields that can be set to
True, False, or ignored.
Use this feature to allow filtering builds by held status (i.e. show
builds that triggered a autohold only) or by voting status (i.e. show only
voting jobs).
Selects let a user choose among predefined values. Use a select to help
a user choose a result value when searching builds and buildsets.
Build page: add a thumbtack icon next to a build's status badge if that
build triggered an autohold.
Change-Id: I40b06c83ed069e0756c7f8b00430d36a36230bfa
7eff6490a4