Inconsistent handling of owner property in item functions

[noahmulfinger]

A lot of the functions in items.ts use different methods for getting the owner property used for creating the correct url. It would be great if we could standardize this as much as possible. Some examples below:

In the updateItem function:

const url = `${getPortalUrl(requestOptions)}/content/users/${
    requestOptions.item.owner
}/items/${requestOptions.item.id}/update`;

In the updateItemResources function:

const owner = requestOptions.owner || requestOptions.authentication.username;
const url = `${getPortalUrl(requestOptions)}/content/users/${owner}/items/${
    requestOptions.id
}/updateResources`;

In the createItemInFolder function:

const owner =
    requestOptions.owner ||
    requestOptions.item.owner ||
    requestOptions.authentication.username;
const baseUrl = `${getPortalUrl(requestOptions)}/content/users/${owner}`;
let url = `${baseUrl}/addItem`;

[jgravois]

resolved in #248