audiopolicy: allow to identify internal strategies by attributes

A unique tag is given to internal strategies to prevent confusion with
default strategy, overwritting volume or mute attribute of these internal
strategies.

Test: make
Bug: 179759299
Bug: 249966139
Signed-off-by: Francois Gaffie <francois.gaffie@renault.com>
Merged-In: I3c08ca3f5445a2da02b25be0e008aa95e46d4289
Change-Id: I61c390787fef88eae24506b60e7cb81680686dc2
(cherry picked from commit 41a82cf1)