1. Remove fluid
2. Remove unused codes
2.1 remove adabert
2.2 remove ddpg controller of NAS
2.3 remove paddleslim.models
2.4 Remove PC-DARTS

* fix key_error in pruner

* add unit test for get_ratios_by_loss

* Make unitest support for Paddle2.0 API.

* Fix demo in static mode

* Remove unused lines

* Fix demo of darts

* fix pruned model save and load, fix bugs of pruning depthwise conv

* add unit test of pruned model save and load

* temp delete

* add unit test

* add some unit tests

* complete autoprune unit test

* add sensitive unit tests

* fix some unit test

* fix auto_pruner.py