Compile modules with `-fobject-code` enabled to byte-code when loaded with `*`...

Compile modules with `-fobject-code` enabled to byte-code when loaded with `*` prefix in ghci (#8042)

The documentation states that when using :add and :load, the `*` prefix forces a module
to be loaded as byte-code. However, this seems to be ignored when -fobject-code has been
enabled. In that case, the compiled code is always used, regardless of whether the *-form
is used.

The idea is to consult the Targets in HscEnv and check the 'targetAllowObjCode' flag. If
the flag for given module is set, then patch up DynFlags and select compilation backend
accordingly.

This would require a linear scan of course, but that shouldn't be too costly.