DEV : Introduce and implement ArrayConstructor

[Pranavchiku]

Towards #3566. This PR adds a new node ArrayConstructor, adds asr verify check for ArrayConstant to only have *Constants, also checks that ArrayConstant cannot have another ArrayConstant.

| ArrayConstructor(expr* args, ttype type, expr? value, arraystorage storage_format)

Lot of lines can be removed from *_ArrayConstant_* that I'll prefer to do in subsequent PRs.

[certik]

Thanks! This requires careful review, I'll try to do it later today. It looks good though from first look.

[certik]

I think that this is fine.

Do tests pass if in is_value_constant in asr_utils.h you change:

        } case ASR::exprType::ArrayConstant: {
            ASR::ArrayConstant_t* array_constant = ASR::down_cast<ASR::ArrayConstant_t>(a_value);
            for( size_t i = 0; i < array_constant->n_args; i++ ) {
                if( !ASRUtils::is_value_constant(array_constant->m_args[i]) &&
                    !ASRUtils::is_value_constant(ASRUtils::expr_value(array_constant->m_args[i])) ) {
                    return false;
                }
            }
            return true;
        }

to:

        } case ASR::exprType::ArrayConstant: {
            return true;
        }

?

This is important for asr verify in this PR to ensure that things are truly constant now.

[Pranavchiku]

I’ll check this in a while. Thanks for reviewing.

[Pranavchiku]

Everything works well locally, let's wait for CI tests.