Cannot deploy realm packages that import "testing" package in non-test source code

[notJoon]

Description

There is an issue where realm packages cannot be deployed when the "testing" package is imported in regular source code (not test files).

For example, assume we created a test helper package as follows:

// PATH: r/testutils/logger.gno
package testutils

import "testing"

func PrintLog(t *testing.T, msg string) {
    t.Helper()
    println(msg)
}

When deploying this package, the following error occurs:

# Run chain
cd gno.land
make fclean && make start.gnoland

# Deploy package
gnokey maketx addpkg -pkgdir path/to/root/r/testutils -pkgpath gno.land/r/testuils -insecure-password-stdin=true -remote localhost:26657 -broadcast=true -chainid dev -gas-fee 100000000ugnot -gas-wanted 100000000

Output:

Enter password.
TX HASH:    
INFO:       vm.version=develop
--= Error =--
Data: invalid gno package; type check errors:
gno.land/r/testutils.gno:5:2: could not import testing (unknown import path "testing")
Msg Traces:
    0  /Users/notJoon/gno-core/tm2/pkg/errors/errors.go:28 - deliver transaction failed: log:msg:0,success:false,log:--= Error =--
Data: vm.TypeCheckError{abciError:vm.abciError{}, Errors:[]string{"gno.land/r/testutils.gno:5:2: could not import testing (unknown import path \"testing\")"}}
Msg Traces:
...

I believe this issue occurs because after the MemPackageType type was added, test files and regular source code are now clearly separated, and during the deployment process, there's a type mismatch with the expected type.

gno/gnovm/pkg/gnolang/mempackage.go

Lines 409 to 425 in 5e6bf29

	type MemPackageType string
	const (
	MPAnyAll MemPackageType = "MPAnyAll" // MPUserAll or MPStdlibAll.
	MPAnyProd MemPackageType = "MPAnyProd" // MPUserProd or MPStdlibProd.
	MPAnyTest MemPackageType = "MPAnyTest" // MPUserTest or MPStdlibTest.
	MPAnyIntegration MemPackageType = "MPAnyIntegration" // MPUserIntegration or MPStdlibIntegration.
	MPStdlibAll MemPackageType = "MPStdlibAll" // stdlibs only, all files.
	MPStdlibProd MemPackageType = "MPStdlibProd" // stdlibs only, no tests/filetests
	MPStdlibTest MemPackageType = "MPStdlibTest" // stdlibs only, w/ tests, w/o integration/filetests
	MPStdlibIntegration MemPackageType = "MPStdlibIntegration" // stdlibs only, only integration tests.
	MPUserAll MemPackageType = "MPUserAll" // no stdlibs, gno pkg path, w/ tests/filetests.
	MPUserProd MemPackageType = "MPUserProd" // no stdlibs, gno pkg path, no tests/filetests.
	MPUserTest MemPackageType = "MPUserTest" // no stdlibs, gno pkg path, w/ tests, w/o integration/filetests.
	MPUserIntegration MemPackageType = "MPUserIntegration" // no stdlibs, only integration tests.
	MPFiletests MemPackageType = "MPFiletests" // filetests only, regardless of file name (tests/files).
	)