test: add a test for short enum syntax across modules (related #12183)

[yuyi98]

This PR add a test for short enum syntax across modules (related #12183).

• Add a test for short enum syntax across modules.
• Modify all the related files.

import net.http

fn main() {
	header := http.new_header_from_map({
		.content_type: 'application/json'
	})

	println(header)
}

PS D:\Test\v\tt1> v run .       
Content-Type: application/json

[spytheman]

Nice.