Only a fraction of a percentage of users are still using
ReplyWidgetPlain, and keeping these modules separate:
* Adds to code complexity
* Adds to ResourceLoader module bloat
* Causes bugs when we use VE dependencies in the
core ReplyWidget class
The disadvantage is that ReplyWidgetPlain will now be
loading all of the VE dependencies, but this will make
switching to visual mode faster.
Bug: T348834
Change-Id: Ifb0cfd43fdab761c3321ad01fa9fefca26473f86
