[upstream_utils] Use pathlib instead of os.path (#7983)

A noteworthy change is the replacement of the `dp.startswith(os.path.join(".", "subdir"))` pattern. pathlib doesn't offer something with similar semantics besides `match` and `full_match`, so there's now a helper function that replicates the behavior.

Other notable changes include the addition of type annotations to ensure code correctness, using == to check file names instead of `endswith` for clarity (`endswith` is still used to check extensions), manual walking and copying being refactored in googletest, json, memory, nanopb, protobuf, and sleipnir to use `walk_cwd_and_copy_if`, and matching functions being shortened to the point where they can just be inlined into the lambda.

Co-authored-by: Tyler Veness <calcmogul@gmail.com>
Co-authored-by: David Vo <auscompgeek@users.noreply.github.com>

upstream_utils/implot.py

@@ -1,37 +1,27 @@
 #!/usr/bin/env python3
 
-import os
 import shutil
+from pathlib import Path
 
 from upstream_utils import Lib, walk_cwd_and_copy_if
 
 
-def matches(dp, f, allowed_files):
-    path = os.path.join(dp, f)
-    return path in allowed_files
-
-
-def walk_and_copy_if_matches(allowed_files, output_directory):
-    walk_cwd_and_copy_if(
-        lambda dp, f: matches(dp, f, allowed_files),
-        output_directory,
-    )
-
-
-def copy_upstream_src(wpilib_root):
-    implot = os.path.join(wpilib_root, "thirdparty", "imgui_suite", "implot")
+def copy_upstream_src(wpilib_root: Path):
+    implot = wpilib_root / "thirdparty/imgui_suite/implot"
 
     # Delete old install
     for d in ["include", "cpp"]:
-        shutil.rmtree(os.path.join(implot, d), ignore_errors=True)
+        shutil.rmtree(implot / d, ignore_errors=True)
 
     # Copy files
     walk_cwd_and_copy_if(
         lambda dp, f: f.endswith(".h"),
-        os.path.join(implot, "include"),
+        implot / "include",
     )
-    walk_and_copy_if_matches(
-        ["./implot_items.cpp", "./implot.cpp"], os.path.join(implot, "cpp")
+    implot_files = [Path("implot_items.cpp"), Path("implot.cpp")]
+    walk_cwd_and_copy_if(
+        lambda dp, f: dp / f in implot_files,
+        implot / "cpp",
     )