[remoting host] Add unit tests for ChromotingHost::BindSessionServices

This CL adds some unit tests for ChromotingHost::BindSessionServices

Change-Id: Ice4841af9d341b76c659fc35a3e2065434bb0f26
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3390510


Reviewed-by: Joe Downing <joedow@chromium.org>
Commit-Queue: Yuwei Huang <yuweih@chromium.org>
Cr-Commit-Position: refs/heads/main@{#959484}