Add constant folding for the shape.rank operation of the shape dialect.
Depends On D82028
LGTM modulo renaming of op (discussed in the dependent patch)
nit: I think llvm::size from STLHelpers.h could make this a bit shorter.
nit: this test doesn't seem to be testing any new functionality that isn't covered by other tests, so it can be omitted.
Rename, address comments
Thanks, didn't see that function.