The bulk of this work is the grand renaming project, from names like
getFoos and setFoos to names like Foo/get and Foo/set. Fortunately, this
makes a number of things simpler, since we no longer have to deal with
both singular and plural object names. fetchRecords has also fallen by
the wayside, as the proper JMAP way to do those is with backreferences.

Note that the internal api names mostly did not change: that is,
ix_get_list_updates is still a method name, instead of ix_query_changes.
We might change these in the future, but decided not to for this time
around.