Move chromeos/dbus/session_manager_client to subdir

Note: The subdir is 'session_manager' instead of the shorter 'session'
to reduce any confusion with components/sessions and to match
components/session_manager (and the process name).

Purely mechanical move in preparation for extracting SessionManagerClient from DBusThreadManager:
./tools/git/move_source_file.py chromeos/dbus/session_manager_client.cc chromeos/dbus/session_manager
./tools/git/move_source_file.py chromeos/dbus/session_manager_client.h chromeos/dbus/session_manager
./tools/git/move_source_file.py chromeos/dbus/fake_session_manager_client.cc chromeos/dbus/session_manager/
./tools/git/move_source_file.py chromeos/dbus/fake_session_manager_client.h chromeos/dbus/session_manager/

Bug: 644350

For bulk mechanical changes:
TBR=sky@chromium.org

Change-Id: I6c831b3cabc38dcf167056fe5016a761cde9a6d3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1526312
Commit-Queue: Steven Bennetts <stevenjb@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#641687}
98 files changed