Remove duplicate SCAG spells

[abc]

The Sword Coast Adventurers Guide contains a number of spells - all of which are also included in Tasha's Cauldron of Everything. Therefore, there's no reason to include the spells from both SCAG and TCE. Additionally, there are no compendiums which reference the SCAG but not TCE. Therefore, the SCAG spell .xml file (spells-scag.xml) is obsolete.

This PR removes the references to the SCAG spell list from collections and additionally removes the spells-scag.xml file.