[Blink] Add GetIssueList API to BuganizerClient

GetIssueList API allows caller to query existing issues with custom query string.
This functionality is needed for tasks such as checking for bug duplication prior to filing new bug.

Bug: 40244594
Change-Id: I9647b6f27881ddeac7223c6941e1c7b9d79acca1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5429724


Reviewed-by: Jonathan Lee <jonathanjlee@google.com>
Commit-Queue: An Sung <ansung@google.com>
Reviewed-by: Weizhong Xia <weizhong@google.com>
Cr-Commit-Position: refs/heads/main@{#1283479}