gh-97669: Move difflib examples to Doc/includes/ (#97964)

Remove diff.py and ndiff.py scripts of Tools/scripts/: move them to
Doc/includes/.

* diff.py and ndiff.py files are no longer executable. Remove also
  their shebang ("#!/usr/bin/env python3").
* Remove the -profile command from ndiff.py to simply the code.
* Remove ndiff.py copyright and history command. The Python
  documentation examples are distributed under the "Zero Clause BSD
  License".

Doc/includes/diff.py

@@ -0,0 +1,59 @@
+""" Command line interface to difflib.py providing diffs in four formats:
+
+* ndiff:    lists every line and highlights interline changes.
+* context:  highlights clusters of changes in a before/after format.
+* unified:  highlights clusters of changes in an inline format.
+* html:     generates side by side comparison with change highlights.
+
+"""
+
+import sys, os, difflib, argparse
+from datetime import datetime, timezone
+
+def file_mtime(path):
+    t = datetime.fromtimestamp(os.stat(path).st_mtime,
+                               timezone.utc)
+    return t.astimezone().isoformat()
+
+def main():
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument('-c', action='store_true', default=False,
+                        help='Produce a context format diff (default)')
+    parser.add_argument('-u', action='store_true', default=False,
+                        help='Produce a unified format diff')
+    parser.add_argument('-m', action='store_true', default=False,
+                        help='Produce HTML side by side diff '
+                             '(can use -c and -l in conjunction)')
+    parser.add_argument('-n', action='store_true', default=False,
+                        help='Produce a ndiff format diff')
+    parser.add_argument('-l', '--lines', type=int, default=3,
+                        help='Set number of context lines (default 3)')
+    parser.add_argument('fromfile')
+    parser.add_argument('tofile')
+    options = parser.parse_args()
+
+    n = options.lines
+    fromfile = options.fromfile
+    tofile = options.tofile
+
+    fromdate = file_mtime(fromfile)
+    todate = file_mtime(tofile)
+    with open(fromfile) as ff:
+        fromlines = ff.readlines()
+    with open(tofile) as tf:
+        tolines = tf.readlines()
+
+    if options.u:
+        diff = difflib.unified_diff(fromlines, tolines, fromfile, tofile, fromdate, todate, n=n)
+    elif options.n:
+        diff = difflib.ndiff(fromlines, tolines)
+    elif options.m:
+        diff = difflib.HtmlDiff().make_file(fromlines,tolines,fromfile,tofile,context=options.c,numlines=n)
+    else:
+        diff = difflib.context_diff(fromlines, tolines, fromfile, tofile, fromdate, todate, n=n)
+
+    sys.stdout.writelines(diff)
+
+if __name__ == '__main__':
+    main()