Revert "Use moveToCodepointOffset for cursor routing" (#16539)
Reverts #16477 , #16497
Issues fixed
None
Issues reopened
Reopens #10960
Reason for revert
Feature turns out to be unstable.
Can this PR be reimplemented? If so, what is required for the next attempt
Use a feature flag
Ensure issues reported in Fix routing to account for rawToContentPos #16497 (comment) and Fix routing to account for rawToContentPos #16497 (comment) are covered by the fix
