IR: Add !nofpclass metadata (#177140)
This adds the analogous metadata to the nofpclass attribute
to assert values are not a certain set of floating-point classes.
This allows the same information to be expressed if a function
argument is passed indirectly. This matches the bitmask encoding
of nofpclass.
I also think this should be allowed for stores to symmetrically handle
sret, but leave that for later.
Alternatively we could add a more expressive !fprange metadata,
but that would be much more complex. It's useful to match the attribute,
and more annotations can always be added.
Fixes #133560
