[8.0] Port the module 'account_move_template' to the new API

This PR contains the module ***account_move_template*** ported to the new API.
Test and installation seems to me ok.

@eLBati if you look at the last version of this code, it does no longer loop on `self` because `self` always has 1 record. 
It can't be `@api.one` because this decorator will call the method for each record and return a concatenated list of the results, so we would have a list of actions instead of one action returning.