Make F401 "unused import" suppressions more specific

In git.compat and git.util.

This applies them individually to each name that is known to be an
unused import, rather than to entire import statements (except
where the entire statement fit on one line and everything it
imported is known to be unused).

Either Ruff has the ability to accept this more granular style of
suppression, or I had been unaware of it from flake8 (used before).
I have veriifed that the suppressions are not superfluous: with no
suppressions, Ruff does warn. This commit makes no change in
git.types because it looks like no suppression at all may be
needed there anymore; that will be covered in the next commit.

This also removes the old `@UnusedImport` comments, which had been
kept before because they were more granular; this specificity is
now achieved by comments the tools being used can recognize.

git/compat.py

@@ -14,18 +14,18 @@
 import os
 import sys
 
-from gitdb.utils.encoding import force_bytes, force_text  # noqa: F401  # @UnusedImport
+from gitdb.utils.encoding import force_bytes, force_text  # noqa: F401
 
 # typing --------------------------------------------------------------------
 
-from typing import (  # noqa: F401
-    Any,
+from typing import (
+    Any,  # noqa: F401
     AnyStr,
-    Dict,
-    IO,
+    Dict,  # noqa: F401
+    IO,  # noqa: F401
     Optional,
-    Tuple,
-    Type,
+    Tuple,  # noqa: F401
+    Type,  # noqa: F401
     Union,
     overload,
 )

git/util.py

@@ -51,16 +51,16 @@
 # gitdb all the time in their imports. They are not in __all__, at least currently,
 # because they could be removed or changed at any time, and so should not be considered
 # conceptually public to code outside GitPython. Linters of course do not like it.
-from gitdb.util import (  # noqa: F401  # @IgnorePep8
-    LazyMixin,  # @UnusedImport
-    LockedFD,  # @UnusedImport
-    bin_to_hex,  # @UnusedImport
-    file_contents_ro_filepath,  # @UnusedImport
-    file_contents_ro,  # @UnusedImport
-    hex_to_bin,  # @UnusedImport
+from gitdb.util import (
+    LazyMixin,  # noqa: F401
+    LockedFD,  # noqa: F401
+    bin_to_hex,  # noqa: F401
+    file_contents_ro_filepath,  # noqa: F401
+    file_contents_ro,  # noqa: F401
+    hex_to_bin,  # noqa: F401
     make_sha,
-    to_bin_sha,  # @UnusedImport
-    to_hex_sha,  # @UnusedImport
+    to_bin_sha,  # noqa: F401
+    to_hex_sha,  # noqa: F401
 )
 
 # typing ---------------------------------------------------------