gh-151876: Add tkinter Canvas methods rotate and rchars (GH-151877)

gh-151876: Add tkinter Canvas methods rotate and rchars (GH-151877)

Wrap the Tk canvas commands "rchars" (replace the text or coordinates of
items, since Tk 8.6) and "rotate" (rotate the coordinates of items about
an origin, new in Tk 9.0) as the methods Canvas.rchars() and
Canvas.rotate(), complementing the existing dchars/insert and move/scale
methods.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>