Build system: Allow specifying Win32 resource include paths using LazyPath

Adds an `include_paths` field to RcSourceFile that takes a slice of LazyPaths. The paths are resolved and subsequently appended to the -rcflags as `/I <resolved path>`.

This fixes an accidental regression from https://github.com/ziglang/zig/pull/19174. Before that PR, all Win32 resource compilation would inherit the CC flags (via `addCCArgs`), which included things like include directories. After that PR, though, that is no longer the case.

However, this commit intentionally does not restore the previous behavior (inheriting the C include paths). Instead, each .rc file will need to have its include paths specified directly and the include paths only apply to one particular resource script. This allows more fine-grained control and has less potentially surprising behavior (at the cost of some convenience).

Closes #19605

test/standalone/windows_resources/build.zig

@@ -10,11 +10,13 @@ pub fn build(b: *std.Build) void {
         .abi = .gnu,
     });
 
-    add(b, b.host, .any, test_step);
-    add(b, target, .any, test_step);
+    const generated_h_step = b.addWriteFile("generated.h", "#define GENERATED_DEFINE \"foo\"");
 
-    add(b, b.host, .gnu, test_step);
-    add(b, target, .gnu, test_step);
+    add(b, b.host, .any, test_step, generated_h_step);
+    add(b, target, .any, test_step, generated_h_step);
+
+    add(b, b.host, .gnu, test_step, generated_h_step);
+    add(b, target, .gnu, test_step, generated_h_step);
 }
 
 fn add(
@@ -22,6 +24,7 @@ fn add(
     target: std.Build.ResolvedTarget,
     rc_includes: enum { any, gnu },
     test_step: *std.Build.Step,
+    generated_h_step: *std.Build.Step.WriteFile,
 ) void {
     const exe = b.addExecutable(.{
         .name = "zig_resource_test",
@@ -32,6 +35,9 @@ fn add(
     exe.addWin32ResourceFile(.{
         .file = b.path("res/zig.rc"),
         .flags = &.{"/c65001"}, // UTF-8 code page
+        .include_paths = &.{
+            .{ .generated = &generated_h_step.generated_directory },
+        },
     });
     exe.rc_includes = switch (rc_includes) {
         .any => .any,

test/standalone/windows_resources/res/zig.rc

@@ -1,3 +1,7 @@
+// This include file is generated via build.zig, and it #defines GENERATED_DEFINE
+#include "generated.h"
+FOO RCDATA { GENERATED_DEFINE }
+
 #define ICO_ID 1
 
 // Nothing from windows.h is used in this .rc file,