Support apiextensions.k8s.io/v1 and admissionregistration.k8s.io/v1

[odp]

Kubernetes v1.22 has discontinued support for apiextensions.k8s.io/v1beta1 and admissionregistration.k8s.io/v1beta1 used by AdaptDL. This MR:

1. Adds support for v1 APIs according to this migration guide
2. Fixes validator service to accept adaptdl.petuum.com/v1, so that it does proper validation of CR request.

v1 is supported from k8s v1.16 onwards. Tested the MR on v1.19 and v1.22

[codecov-commenter]

Codecov Report

Merging #118 (91cec08) into master (4d8afa5) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #118   +/-   ##
=======================================
  Coverage   61.39%   61.39%           
=======================================
  Files          32       32           
  Lines        2531     2531           
  Branches      416      416           
=======================================
  Hits         1554     1554           
  Misses        896      896           
  Partials       81       81           

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