DevTools [Search]: making search tool keyboard navigable
DevTools [Search]: making search tool keyboard navigable

Re-upload of https://chromium-review.googlesource.com/c/chromium/src/+/1819493 to the DevTools repository

Issue:
- Search tool is not keyboard accessible

Changes:
- First search result is selected by default
- Pressing enter on a search result will perform the navigation

Bug: 963183
Change-Id: I4fdaf44ed6aec75cac4a92ff163e1d3ea38058d8
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/1873129
Reviewed-by: Lorne Mitchell <b024a4e2ee56b9b5450225fa7affa8f95408a018@microsoft.com>
Commit-Queue: Michael Liao <00d75d81082fdf74688ec453c516b42f7cbf0f40@microsoft.com>

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