Auto merge of #11899 - ConnorGBrewster:app_packaging, r=larsbergstrom

Create Servo.app and dmg on mac package

<!-- Please describe your changes on the following line: -->
This creates Servo.app and puts it in a dmg along with a symlink to `/Applications`.

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

<!-- Either: -->
- [ ] There are tests for these changes OR
- [X] These changes do not require tests because creating packager

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

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This change is [<img src="https://reviewable.io/review_button.svg" height="35" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/11899)
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components/util/resource_files.rs

@@ -39,20 +39,13 @@ pub fn resources_dir_path() -> PathBuf {
     let mut path = env::current_exe().expect("can't get exe path");
     // Follow symlink
     path = path.canonicalize().expect("path does not exist");
-    path.pop();
-    path.push("resources");
-    if !path.is_dir() {   // resources dir not in same dir as exe?
-        // exe is probably in target/{debug,release} so we need to go back to topdir
-        path.pop();
-        path.pop();
-        path.pop();
+
+    while path.pop() {
         path.push("resources");
-        if !path.is_dir() {
-            // exe is probably in target/$target_triple/{debug,release} so go back one more
-            path.pop();
-            path.pop();
-            path.push("resources");
+        if path.is_dir() {
+            break;
         }
+        path.pop();
     }
     *dir = Some(path.to_str().unwrap().to_owned());
     path