tests: unify all temporary files/folders under $VTMP/v, that can be cleaned by v wipe-cache (#15774)

cmd/tools/vwipe-cache.v

@@ -2,12 +2,18 @@ module main
 
 import os
 import v.vcache
+import v.util
 
 fn main() {
-	mut cm := vcache.new_cache_manager([])
-	cpath := cm.basepath
+	wipe_path(vcache.new_cache_manager([]).basepath, 'V cache')
+	wipe_path(util.get_vtmp_folder(), 'V tmp.c')
+	wipe_path(os.join_path(os.temp_dir(), 'v'), 'V tests')
+}
+
+fn wipe_path(cpath string, label string) {
 	if os.exists(cpath) && os.is_dir(cpath) {
 		os.rmdir_all(cpath) or {}
 	}
-	println('V cache folder $cpath was wiped.')
+	os.mkdir_all(cpath) or {}
+	println('$label folder $cpath was wiped.')
 }