[SEH] Emit 32-bit SEH tables for the new EH IR

[SEH] Emit 32-bit SEH tables for the new EH IR

The 32-bit tables don't actually contain PC range data, so emitting them
is incredibly simple.

The 64-bit tables, on the other hand, use the same table for state
numbering as well as label ranges. This makes things more difficult, so
it will be implemented later.

llvm-svn: 247192