GLSL: clean up GLSL output whitespace generation.

More line() and less std::endl.
More automated indents and less manual spacing.
Put a single newline after every struct and function declaration.

Note that this does touch every test result, but only affects whitespace.

Change-Id: I7506b9029b79b91fb335911dba44369b36f09bbe
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/78300
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
diff --git a/test/expressions/binary/add/vec3-scalar/i32.wgsl.expected.glsl b/test/expressions/binary/add/vec3-scalar/i32.wgsl.expected.glsl
index 7882f3b..b13d477 100644
--- a/test/expressions/binary/add/vec3-scalar/i32.wgsl.expected.glsl
+++ b/test/expressions/binary/add/vec3-scalar/i32.wgsl.expected.glsl
@@ -7,8 +7,8 @@
   ivec3 r = (a + 4);
   return;
 }
+
 void main() {
   f();
 }
 
-