Add isProtected flag to Output

Allow outputs to decide if they want to render protected content, not
just if they support it. The current code checks if the Output is secure
when deciding whether to render protected content. By adding a new flag,
it will allow displays to decide if they want to render secure,
protected, or both.

This code doesn't have a way to create displays with only protected and
will still rely on the isSecure flag to ensure backwards compatibility.

Test: presubmit
Fixes: 285553970
Fixes: 300492271
Change-Id: If5e65388825d37f4ddaea5190259a136cfa89264