tools: add tests for v where; improve usability (#15059)

cmd/tools/vwhere/test/file_one.v

@@ -0,0 +1,28 @@
+module test
+
+// Test declarations
+
+fn main() {
+	p_1 := Programmer{'Programmer', 'Inmutable'}
+	mut p_2 := Programmer{'Programmer', 'Mutable'}
+}
+
+struct Programmer {
+	f_name string
+	l_name string
+}
+
+fn (p Programmer) drink(cups int) string {
+	return 'drink coffee, return program'
+}
+
+pub struct Brogrammer {
+	f_name string
+	life   []Stories
+}
+
+pub fn (p Brogrammer) drink(glasses int) string {
+	return 'drink beer, return script cluster'
+}
+
+struct Stories {}

cmd/tools/vwhere/test/file_two.v

@@ -0,0 +1,29 @@
+module test
+
+const (
+	x = 10
+	y = 100
+	z = 1000
+)
+
+pub enum Public {
+	importable
+	shareable
+}
+
+enum Private {
+	storable
+	donwloadable
+}
+
+interface Drinker {
+	drink(int) string
+}
+
+pub fn sprint(dkr Drinker) {
+	println(drk.drink(6))
+}
+
+fn some_function_name(foo string, bar int) string {
+	return 'baz'
+}

cmd/tools/vwhere/test/nested_mod/nested_file.v

@@ -0,0 +1,7 @@
+module nested_mod
+
+pub const (
+	a = 30
+	b = 60
+	c = 120
+)