vfmt: change all '$expr' to '${expr}' (#16428)

vlib/builtin/sorting_test.v

@@ -7,14 +7,14 @@ const (
 fn test_sorting_simple() {
 	mut a := unsorted.clone()
 	a.sort()
-	println(' a: $a')
+	println(' a: ${a}')
 	assert a == sorted_asc
 }
 
 fn test_sorting_with_condition_expression() {
 	mut a := unsorted.clone()
 	a.sort(a > b)
-	println(' a: $a')
+	println(' a: ${a}')
 	assert a == sorted_desc
 }
 
@@ -44,7 +44,7 @@ fn mysort(mut a []int) {
 fn test_sorting_by_passing_a_mut_array_to_a_function() {
 	mut a := unsorted.clone()
 	mysort(mut a)
-	println(' a: $a')
+	println(' a: ${a}')
 	assert a == sorted_asc
 }
 
@@ -59,10 +59,10 @@ fn test_sorting_by_passing_an_anonymous_sorting_function() {
 fn test_sorting_u64s() {
 	mut a := [u64(3), 2, 1, 9, 0, 8]
 	a.sort()
-	println(' a: $a')
+	println(' a: ${a}')
 	assert a == [u64(0), 1, 2, 3, 8, 9]
 	a.sort(a > b)
-	println(' a: $a')
+	println(' a: ${a}')
 	assert a == [u64(9), 8, 3, 2, 1, 0]
 }