fws: Make fws policy available to lacros

This CL exposes the floating workspace (fws) enabled policy to be
seen on the lacros side.

A followup CL will use this policy flag to tie some aspects of
Desk Profiles with fws to allow filtering of windows by profile.

Low-Coverage-Reason: TRIVIAL_CHANGE This is a renaming.

BUG=b:323015572
TEST=Manual Test and CQ Dryruns

Change-Id: I3e7afa27825f8b958989fb5bb3a15508cf74fc2f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5263668
Reviewed-by: April Zhou <aprilzhou@google.com>
Commit-Queue: Matthew Zhu <zhumatthew@google.com>
Reviewed-by: Pavol Marko <pmarko@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Cait Phillips <caitkp@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1261318}