Summary:
Adds yaml configs to train selected methods on CO3Dv2.
Few more updates:
1) moved some fields to base classes so that we can check is_multisequence in experiment.py
2) skip loading all train cameras for multisequence datasets, without this, co3d-fewview is untrainable
3) fix bug in json index dataset provider v2
Reviewed By: kjchalup
Differential Revision: D38952755
fbshipit-source-id: 3edac6fc8e20775aa70400bd73a0e6d52b091e0c
1163eaab43