stitch preprocessing pipeline

Summary:
1. add call to binarization to complete preprocessing pipeline
2. add ability to specify task to select the dictionary, and add a bert task
3. Get rid of function calls that are no longer needed after moving functions from fairseq here

Reviewed By: jingfeidu

Differential Revision: D13977842

fbshipit-source-id: ec9bbb4e98e62e12c20ba68bb52b8bcc94aee91d