Fix bug where some requests send a `next_marker` query parameter instead of `marker`

[PJSimon]

• [X] I've read, understood, and done my best to follow the *CONTRIBUTING guidelines.

What did you do?

This bug is on the Objective-C Maintenance branch.

It looks like this PR was made, in error: https://github.com/box/box-ios-sdk/pull/385 When requesting Recent Items, the name of the marker query parameter for this request is, in fact, marker, not next_marker, which is the name of the marker value that is returned in the response.

It appears that deprecating marker introduced a bug. The result is that a second page of recent items can't be retrieved. It's possible that the response is never more than one page, so it was never discovered until now.

What did you expect to happen?

Request should use marker query parameter. We should scan for other cases of this bug in the SDK. There should be a test for this.

What happened instead?

Request uses next_marker query parameter. There could be other instances of this bug in the SDK. There's no test for it.