Events filtering improvements

[tzununbekov]

1. Values passed with --eventTypes flag now can contain * symbol as a prefix or suffix to set trigger's filtering condition to "prefix" or "suffix" accordingly, related to Support prefix & suffix trigger filters in tmctl #215,
2. tmctl create trigger supports --filter argument which, if passed, will be encoded directly into filter structure and passed to trigger specification, e.g.:

   tmctl create trigger --target sockeye --filter '{"Not":{"Exact":{"source":"foo"}}}'
   

3. tmctl describe updated to work with new possible triggers output