fmt: use single quotes around fixed string arr default expr (#7581)

vlib/v/fmt/fmt.v

@@ -1840,7 +1840,9 @@ pub fn (mut f Fmt) array_init(it ast.ArrayInit) {
 		}
 		f.write(f.table.type_to_str(it.elem_type))
 		if it.has_default {
-			f.write('{init: $it.default_expr}')
+			f.write('{init: ')
+			f.expr(it.default_expr)
+			f.write('}')
 		} else {
 			f.write('{}')
 		}

vlib/v/fmt/tests/array_init_keep.vv

@@ -16,6 +16,10 @@ fn main() {
 		'eggs',
 	]
 	_ := []int{len: 10, cap: 10, init: 7}
-	_ := []map[string]string{len: 5, cap: 50, init: 'a'}
-	_ := []map[string][]int{len: 7, cap: 100, init: [1, 2]}
+	_ := []map[string]string{len: 5, cap: 50, init: {
+		'a': 'a'
+	}}
+	_ := []map[string][]int{len: 7, cap: 100, init: {
+		'a': [1, 2]
+	}}
 }

vlib/v/fmt/tests/fixed_size_array_type_keep.vv

@@ -1,3 +1,7 @@
 fn foo() [1]f32 {
 	return [f32(0.0)]!!
 }
+
+fn main() {
+	_ := [5]string{init: 'abc'}
+}