Deprecate `configure_set` & make `configure_sets` work for single params.

## Bevy version
0.11

## What you did
Tried to use `.configure_sets` with a single system set parameter.

## What went wrong
Received a compile error. It seems `configure_set` was not deprecated and `configure_sets` was not changed to support single item calls like other APIs in this family for `0.11`.