Optimize multi patch when $returning is false.

[DaddyWarbucks]

I noticed this while making this comment: https://github.com/feathersjs/feathers/pull/2472#issuecomment-1008349932

I believe we are potentially wasting some calls to _getOrFind if the user is using $returning: false. Note here: https://github.com/feathersjs-ecosystem/feathers-sequelize/blob/db4b5ff9b89df9b163f9cd5d8c32de8c915ff71c/lib/index.js#L222 that we are fetching the idList so that the modified results can be returned. But, we don't know for certain that the results need to be returned until https://github.com/feathersjs-ecosystem/feathers-sequelize/blob/db4b5ff9b89df9b163f9cd5d8c32de8c915ff71c/lib/index.js#L245

We should move some code around so that we are not fetching the idList until we check if params.$returning !== false. The _remove method does this. So we should update patch to work similarly.

[fratzinger]

don't forget about #363 and #364

[fratzinger]

https://github.com/feathersjs-ecosystem/feathers-sequelize/blob/db4b5ff9b89df9b163f9cd5d8c32de8c915ff71c/lib/index.js#L248 Should be return Promise.resolve(id == null ? [] : null) Same here: https://github.com/feathersjs-ecosystem/feathers-sequelize/blob/db4b5ff9b89df9b163f9cd5d8c32de8c915ff71c/lib/index.js#L300

Or should $returning only supported for multi requests? If so, we need to handle this as well, like: https://github.com/feathersjs-ecosystem/feathers-sequelize/blob/db4b5ff9b89df9b163f9cd5d8c32de8c915ff71c/lib/index.js#L293 if (params.$returning !== false && id == null)

[DaddyWarbucks]

Maybe relevant: https://github.com/feathersjs-ecosystem/feathers-sequelize/issues/405