limit the overrides in the shader interface, to those that are "statically accessed"

[dneto0]

The definition of "statically accessed" is now recursive in more interesting ways, to make sure it pulls in the right set of overrides.

gpuweb/gpuweb#3600

[dj2]

Is there a test that can be written for this? If we use the override it's accessed .... if we don't use it, how do we test that it wasn't included?

[kainino0x]

I'm not sure what the behavior is supposed to be here. See gpuweb/gpuweb#4624

[dj2]

Obsolete