TIAF script fixes (#3044)

* Fix typo in MARS document key.

Signed-off-by: John <jonawals@amazon.com>

* Add diff support for commits on different branches.

Signed-off-by: John <jonawals@amazon.com>

* Restore archiving of historic data objects.

Signed-off-by: John <jonawals@amazon.com>

* Correctly handle commit diffs for PR builds.

Signed-off-by: John <jonawals@amazon.com>

* Comment out archiving of historic data objects.

Signed-off-by: John <jonawals@amazon.com>

* Fix python typo

Signed-off-by: John <jonawals@amazon.com>

* Remove comment pertaining to s3 bucket.

Signed-off-by: John <jonawals@amazon.com>

* Fix test selection efficiency for MARS.

Signed-off-by: John <jonawals@amazon.com>

scripts/build/TestImpactAnalysis/git_utils.py

@@ -21,12 +21,14 @@ class Repo:
         branch = self._repo.active_branch
         return branch.name
 
-    def create_diff_file(self, src_commit_hash: str, dst_commit_hash: str, output_path: pathlib.Path):
+    def create_diff_file(self, src_commit_hash: str, dst_commit_hash: str, output_path: pathlib.Path, multi_branch: bool):
         """
         Attempts to create a diff from the src and dst commits and write to the specified output file.
 
         @param src_commit_hash: The hash for the source commit.
         @param dst_commit_hash: The hash for the destination commit.
+        @param multi_branch:    The two commits are on different branches so view the changes on the 
+                                branch containing and up to dst_commit, starting at a common ancestor of both.
         @param output_path:     The path to the file to write the diff to.
         """
 
@@ -39,8 +41,15 @@ class Repo:
         except EnvironmentError as e:
             raise RuntimeError(f"Could not create path for output file '{output_path}'")
 
+        args = ["git", "diff", "--name-status", f"--output={output_path}"]
+        if multi_branch:
+            args.append(f"{src_commit_hash}...{dst_commit_hash}")
+        else:
+            args.append(src_commit_hash)
+            args.append(dst_commit_hash)
+
         # git diff will only write to the output file if both commit hashes are valid
-        subprocess.run(["git", "diff", "--name-status", f"--output={output_path}", src_commit_hash, dst_commit_hash])
+        subprocess.run(args)
         if not output_path.is_file():
             raise RuntimeError(f"Source commit '{src_commit_hash}' and/or destination commit '{dst_commit_hash}' are invalid")