fix issue with two votes on the same date

fix issue with header not showing correct vote date
split logic for Persistence into different files
create class that deals with voting time, existing votes, and what should be shown based on that

Shared/Persisence/PersistenceDELETE.swift

@@ -0,0 +1,29 @@
+//
+//  PersistenceDELETE.swift
+//  Feels
+//
+//  Created by Trey Tartt on 2/17/22.
+//
+
+import CoreData
+
+extension PersistenceController {
+    func clearDB() {
+        let fetchRequest: NSFetchRequest<NSFetchRequestResult> = NSFetchRequest(entityName: "MoodEntry")
+        let deleteRequest = NSBatchDeleteRequest(fetchRequest: fetchRequest)
+        
+        do {
+            try viewContext.executeAndMergeChanges(using: deleteRequest)
+            try viewContext.save()
+        } catch let error as NSError {
+            fatalError("Unresolved error \(error), \(error.userInfo)")
+        }
+    }
+    
+    func delete(forDate: Date) {
+        if let entry = PersistenceController.shared.getEntry(byDate: forDate) {
+            viewContext.delete(entry)
+            try! viewContext.save()
+        }
+    }
+}