parser: fix assigning with in another module sumtypes (fix #19413)

[yuyi98]

This PR fix assigning with in another module sumtypes (fix #19413).

• Fix assigning with in another module sumtypes.
• Add test.

aa/aa.v

module aa

pub type MySumType = S1 | S2

pub struct S1 {}

pub struct S2 {}

tt1.v

import aa

fn main() {
	node := aa.MySumType(aa.S1{})

	cond := node in [aa.S1, aa.S2]
	mut b := 'b'
	mut c := 'c'

	if cond {
		println('${cond} --- ${b} --- ${c}')
		assert '${cond} --- ${b} --- ${c}' == 'true --- b --- c'
	} else {
		assert false
	}
}

PS D:\Test\v\tt1> v run .
true --- b --- c

[spytheman]

Oof, very good find.