This patch add the conversion pattern for fir.extract_value
and fir.insert_value. fir.extract_value is lowered to llvm.extractvalue
anf fir.insert_value is lowered to llvm.insertvalue.
This patch also adds the type conversion for the BoxType and RecordType
needed to have some comprehensive tests.
This patch is part of the upstreaming effort from fir-dev branch.
(this is the canonical/generic way of handling constants)