Convert omnibox_popup_egtests to EG2.

* Ensures omnibox popup_egtests compat with EG2
* Converts and moves necessary matchers to work through eDO
* Moves certain constants to separate targets to reduce transitive deps
* Adds a new EG2 target and adds popup eg2 tests to ios_chrome_eg2tests

Bug: 866147
Change-Id: Ie5383acfdda58dd76535535bce6a624b4f6e342b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1699673
Reviewed-by: edchin <edchin@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Stepan Khapugin <stkhapugin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#677276}