fmt: remove tail space when using multiline short arg (#9110)

vlib/v/fmt/fmt.v

@@ -2176,6 +2176,14 @@ pub fn (mut f Fmt) struct_init(node ast.StructInit) {
 		fields_start := f.out.len
 		fields_loop: for {
 			if !single_line_fields {
+				if use_short_args && f.out.buf[f.out.buf.len - 1] == ` ` {
+					//           v Remove space at tail of line
+					// f(a, b, c, \n
+					//     f1: 0\n
+					//     f2: 1\n
+					// )
+					f.out.go_back(1)
+				}
 				f.writeln('')
 				f.indent++
 			}

vlib/v/fmt/tests/fn_trailing_arg_syntax_expected.vv

@@ -6,6 +6,7 @@ struct Bar {
 
 struct Baz {
 	x int
+	y int
 }
 
 fn main() {
@@ -18,8 +19,13 @@ fn main() {
 		x: 'some string'
 		b: Baz{
 			x: 0
+			y: 0
 		}
 	)
+	baz_func('foo', 'bar',
+		x: 0
+		y: 0
+	)
 	ui.row(
 		// stretch: true
 		margin: {
@@ -33,3 +39,5 @@ fn main() {
 
 fn bar_func(bar Bar) {
 }
+
+fn baz_func(a string, b string, baz Baz) {}

vlib/v/fmt/tests/fn_trailing_arg_syntax_input.vv

@@ -6,6 +6,7 @@ struct Bar {
 
 struct Baz {
 	x int
+	y int
 }
 
 fn main() {
@@ -13,7 +14,11 @@ fn main() {
 	bar_func(x: 'a very long content should cause vfmt to use multiple lines instead of one.', y: 123456789)
 	bar_func(x: 'some string', b: Baz{
 		x: 0
+		y: 0
 	})
+	baz_func('foo', 'bar', x: 0
+		y: 0
+	)
 	ui.row({
 		//stretch: true
 		margin: {top:10,left:10,right:10,bottom:10}
@@ -22,3 +27,5 @@ fn main() {
 
 fn bar_func(bar Bar) {
 }
+
+fn baz_func(a string, b string, baz Baz) {}