Revert "Move the Block helper type to its own file"

This fixes the broken tests

This reverts commit 286ae68fd6.

nostrdb/NdbNote.swift

@@ -415,15 +415,7 @@ extension NdbNote {
         // Rely on Apple's NLLanguageRecognizer to tell us which language it thinks the note is in
         // and filter on only the text portions of the content as URLs and hashtags confuse the language recognizer.
         let originalBlocks = self.blocks(privkey).blocks
-        let originalOnlyText = originalBlocks.compactMap {
-                if case .text(let txt) = $0 {
-                    return txt
-                }
-                else {
-                    return nil
-                }
-            }
-            .joined(separator: " ")
+        let originalOnlyText = originalBlocks.compactMap { $0.is_text }.joined(separator: " ")
 
         // Only accept language recognition hypothesis if there's at least a 50% probability that it's accurate.
         let languageRecognizer = NLLanguageRecognizer()