move quote model to libsession

libsession/src/main/java/org/session/libsession/messaging/sending_receiving/quotes/QuoteModel.kt

@@ -0,0 +1,11 @@
+package org.session.libsession.messaging.sending_receiving.quotes
+
+import org.session.libsession.messaging.messages.visible.Attachment
+import org.session.libsession.messaging.threads.Address
+
+class QuoteModel(val id: Long,
+                 val author: Address,
+                 val text: String,
+                 val missing: Boolean,
+                 val attachments: List<Attachment>?) {
+}