refactor(protected-phrases): extract config and text normalization helpers

python/ebook_search/protected_phrases/config/bad_starts.toml

@@ -0,0 +1,27 @@
+tokens = [
+    "a",
+    "an",
+    "did",
+    "didn't",
+    "he",
+    "here",
+    "how",
+    "i",
+    "it",
+    "she",
+    "that",
+    "the",
+    "there",
+    "they",
+    "this",
+    "we",
+    "what",
+    "when",
+    "where",
+    "which",
+    "who",
+    "whom",
+    "whose",
+    "why",
+    "you",
+]