[upstream_utils] Refactor upstream_utils scripts (#4367)

* Root folder variable names are now more descriptive
* clone_repo() now restores the current working directory
* Removed setup_upstream_repo() since it's now identical to clone_repo()
* Moved am_patches()'s for loop into user scripts so the filename prefix
  doesn't need to be included in every patch filename
* Renamed am_patches() to git_am() since its only job now is to run "git am"
* Removed unused apply_patches() function
* Fixed typo in git_am()'s ignore_whitespace arg name

upstream_utils/update_fmt.py

@@ -4,28 +4,26 @@ import os
 import shutil
 
 from upstream_utils import (
-    setup_upstream_repo,
+    get_repo_root,
+    clone_repo,
     comment_out_invalid_includes,
     walk_cwd_and_copy_if,
-    am_patches,
+    git_am,
 )
 
 
 def main():
-    root, repo = setup_upstream_repo("https://github.com/fmtlib/fmt", "9.0.0")
-    wpiutil = os.path.join(root, "wpiutil")
+    upstream_root = clone_repo("https://github.com/fmtlib/fmt", "9.0.0")
+    wpilib_root = get_repo_root()
+    wpiutil = os.path.join(wpilib_root, "wpiutil")
 
-    # Apply patches to original git repo
-    prefix = os.path.join(root, "upstream_utils/fmt_patches")
-    am_patches(
-        repo,
-        [
-            os.path.join(prefix, "0001-Don-t-throw-on-write-failure.patch"),
-            os.path.join(
-                prefix, "0002-Suppress-clang-tidy-warning-false-positive.patch"
-            ),
-        ],
-    )
+    # Apply patches to upstream Git repo
+    os.chdir(upstream_root)
+    for f in [
+        "0001-Don-t-throw-on-write-failure.patch",
+        "0002-Suppress-clang-tidy-warning-false-positive.patch",
+    ]:
+        git_am(os.path.join(wpilib_root, "upstream_utils/fmt_patches", f))
 
     # Delete old install
     for d in [