Remove flags from Java side.

This simplifies the code quite a bit.
- GERMAN_UMLAUTS are now handled through a key-value attribute.
  The dictionary generator does not need to know about it any more.
- FRENCH_LIGATURES are deprecated as we handle them with shortcuts now.
- CONTAINS_BIGRAMS is deprecated. Bigram processing is always applied
  regardless of this flag.

Bug: 11281748
Change-Id: I55a11ba61d3589c1584a3fa6c941374b349b7b5c