Entirely reworked text handling pipeline

This breaks the text pipeline into the following pieces:

- input parsing (split known bracketed phoneme sections out first)

- normalization (fix spacing, numbers, abbreviations, etc.)

- phonetization (do CMUdict lookup or g2p prediction)

- sequencing (convert the symbolic representation to integer
  representation)

Each "pipeline" can have a unique combination of operations for each of
these pipeline steps.

This will grow over time.

tts/text/pipeline_components/phonetization/base_phonetization.py

@@ -0,0 +1,19 @@
+
+import re
+from typing import List
+from text.pipeline_components.phonetization.cmudict import CMUDict
+
+# Regex taken from open source tacotron2 extensions
+# NB: This was broken and couldn't handle apostrophes
+#_arpabet_split_re = re.compile(r'[^\s]*{.*?}[^\s]*|[\w]+|[^\w\s]+')
+
+# Modified regex to not split apostrophe (eg. "you're", "I'm", etc.) or hyphenation (eg "avant-garde")
+_arpabet_split_re = re.compile(r'[^\s]*{.*?}[^\s]*|[\w]+\'[\w]+|[\w]+\-[\w]+|[\w]+|[^\w\s]+')
+
+class BasePhonetization:
+    def __init__(self, phoneme_dictionary: CMUDict):
+        self.phoneme_dictionary = phoneme_dictionary
+
+    def _split_grapheme_sentence_to_words(self, text_sequence: str) -> List[str]:
+        """Split a grapheme word sequence to individual grapheme words"""
+        return [word for word in _arpabet_split_re.findall(text_sequence)]