And while moving it, get rid of the 'drawinglyer::tools' subnamespace.
Less potential confusion with the global 'tools' namespace.

Change-Id: Iab3c25be0cec7f3d182228d122837e9f2ac9a529
Reviewed-on: https://gerrit.libreoffice.org/42619Reviewed-by: Tor Lillqvist <tml@collabora.com>
Tested-by: Tor Lillqvist <tml@collabora.com>