[Commerce 1.x] Provide a process plugin to map order status

Problem/Motivation

In Commerce 1.x, orders had different status items than in 2.x. While this could be handled in the migration template, I think it makes more sense to provide a process plugin that maps 1.x status to the 2.x status.

Proposed resolution

Create a migrate process plugin that maps 1.x statuses to 2.x statuses. This can then be extended by custom migrations to easily handle custom workflows made in 1.x