Invalid IR test errors

[99NIMI]

module.verify() will report errors if our generetad IR is not valid
this verification can either be activated by "cargo test --features=verify" or in cargo.toml

failing tests

• codegen::tests::debug_tests::expression_debugging::external_impl_added_as_external_subroutine

• resolver::tests::const_resolver_tests::const_enum_variable_default_value_compile_time_evaluation #696

• codegen::tests::code_gen_tests::typed_enums_with_partly_initializers_are_generated #697

• codegen::tests::function_tests::function_with_ref_sized_string_varargs_called_in_program #736

• codegen::tests::function_tests::passing_arguments_to_functions_by_ref_and_val #698

• codegen::tests::string_tests::function_returning_generic_string_should_return_by_ref

• codegen::tests::string_tests::using_a_constant_var_string_should_be_memcpyable

• codegen::tests::typesystem_test::small_int_varargs_get_promoted_while_32bit_and_higher_keep_their_type

• correctness::datatypes::function_return_string_by_ref_via_inout

• correctness::external_functions::string_sized_pointer_variadic_call

• correctness::external_functions::sized_pointer_variadic_call

• correctness::functions::by_ref_and_by_val_mixed_function_call

• correctness::strings::string_as_function_parameters

• correctness::strings::string_as_function_parameters_cast

• correctness::strings::string_as_function_parameters_internal

• correctness::strings::wstring_as_function_parameters

• correctness::strings::wstring_as_function_parameters_cast

• correctness::strings::assigning_global_strings_in_program_by_passing_sized_strigs

• correctness::functions::mux_string_literal