bpo-33855: Still more edits and minimal tests for IDLE  (GH-7784)


Part 3 of 3, continuing PR GH-7689. This covers 14 idlelib modules and their tests,
rpc to zoomheight except for run (already done) and tooltip (being done separately).
(cherry picked from commit 4d92158f4c3917fc4fbfebff15224e74782abf79)

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
36 files changed