Related to #1491

Consolidate spo site list and spo site classic list commands into spo site list which lists both modern and classic sites. The output should contain combined information from both APIs used by the spo site classic list and spo site list commands. Additionally, mark the spo site classic list command as deprecated so that we can remove it in v3.

Once this item is done, let's create a new item linked to milestone v3 to remove the deprecated spo site classic list command.