Assigns a role to a member.
The assignRole() function returns a Promise that resolves when the
specified role is assigned to the specified member.
roleId must be an ID from an existing role in your site.
The role ID can be copied from the Role Settings page.
You can access the Role Settings page from your site's
Member Permissions
page.
Note: This function may take a few seconds until the role is assigned and the promise is resolved.
ID of the role to assign to the member.
ID of the member to assign the role to.
Authorization options.