[Attributor][PM] Introduce `-attributor-enable={none,cgscc,module,all}`

The old command line option `-attributor-disable` was too coarse grained
as we want to measure the effects of the module or cgscc pass without
the other as well.

Since `none` is the default there is no real functional change.

Reviewed By: lebedev.ri

Differential Revision: https://reviews.llvm.org/D78571