create EditTextOnly state

reason: Edit state already exists, but it accepts any message,
but there is need in ability to accept only text, for example for
button editing

src/main.rs

@@ -71,6 +71,10 @@ pub enum State {
         lang: String,
         is_caption_set: bool,
     },
+    EditTextOnly {
+        literal: String,
+        lang: String,
+    },
     EditButton,
 }