gh-120083: Add IDLE Hovertip foreground color needed for recent macOS (#120605)

On recent versions of macOS (sometime between Catalina and Sonoma 14.5), the default Hovertip foreground color changed from black to white, thereby matching the background. This might be a matter of matching the white foreground of the dark-mode text. The unreadable result is shown here (#120083 (comment)).

The foreground and background colors were made parameters so we can pass different colors for future additional hovertips in IDLE.
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Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>