[wallpaper search] Fix truncation of combobox options.

1. Allow combobox options to take up to two lines
   before hiding their overflow.
2. Allow truncated strings to be viewed in their entirety,
   by giving them a tooltip (via their CSS "title" attributes).

* Note: While `-webkit-line-clamp` would give us tighter
control over the number of lines shown, we can't use it
because `-webkit-box` usage has been deprecated. [1]

Before: screen/5rhZSNjVEufVMWm
After: screen/5Y8WnaBD2JBQoRM

[1] screen/4XNjqzHiTY7jHZD

Change-Id: I260675739c49fa6c70dae47edea3df3aa045ec6b
Bug: 361600217, 360124606
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5805939
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Reviewed-by: Tibor Goldschwendt <tiborg@chromium.org>
Commit-Queue: Paul Adedeji <pauladedeji@google.com>
Cr-Commit-Position: refs/heads/main@{#1345657}