[ja] Refactor Japanese transforms names and add English descriptions (#…

…1007)

* add -rya -cha -n

* add tests

* fix typos

* resolve merge conflicts

* add tests

* change to -ya with chaining

* fix -ge and add -garu

* add descriptions

* descriptions done

* add back imperative negative

* fix description

* add string var

* remove form

* revert back to volitional

* -ku

* remove new causative

* revert to negative and clarify -n

* fix tests

* clarify some desc

* fix test