✨ feat(processor): implement rule processor

- implements struct `Processor` to manage rules for trashing messages
- adds method `trash_messages` to list and trash messages with labels and queries

src/processor.rs

@@ -0,0 +1,34 @@
+// use crate::EolRule;
+
+use crate::{Result, Trash, config::EolRule};
+
+/// Rule processor
+#[derive(Debug)]
+pub struct Processor {
+    credential_file: String,
+    rule: EolRule,
+}
+
+impl Processor {
+    fn new(credential_file: String, rule: EolRule) -> Self {
+        Processor {
+            credential_file,
+            rule,
+        }
+    }
+
+    async fn trash_messages(&self, label: &str) -> Result<()> {
+        let mut messages_to_trash = Trash::new(&self.credential_file).await?;
+
+        messages_to_trash
+            .message_list()
+            .add_labels(&self.credential_file, &[label.to_string()])
+            .await?;
+
+        messages_to_trash
+            .message_list()
+            .set_query(&self.rule.eol_query());
+
+        messages_to_trash.run(0).await
+    }
+}