writers: Use the new sem::Module::DependencyOrderedDeclarations

As the resolver currently enforces in-order declarations, this does not
change the declaration order from iterating over the
ast::Module::GlobalDeclarations.

The MSL backend has been changed to use the
sem::Module::DependencyOrderedDeclarations list instead of looping over
different declaration types separately.

Bug: tint:1266
Change-Id: I698d612032285311017bfceab3c42adae1928a0e
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79767
Reviewed-by: James Price <jrprice@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>

test/buffer/uniform/static_index/read.wgsl.expected.msl

@@ -16,9 +16,11 @@ struct Inner {
   /* 0x0000 */ int x;
   /* 0x0004 */ int8_t tint_pad[12];
 };
+
 struct tint_array_wrapper {
   /* 0x0000 */ Inner arr[4];
 };
+
 struct S {
   /* 0x0000 */ packed_int3 a;
   /* 0x000c */ int b;