Support save & load from hdfs in orca estimators (#4283)
Support save & load from hdfs in orca estimators (#4283)

* refactor

* support multi fs in orca estimators

* fix style

* fix tests

* fix tests

* support static method

* fix style
yangw1234/BigDL,intel-analytics/BigDL,yangw1234/BigDL,yangw1234/BigDL,intel-analytics/BigDL,intel-analytics/BigDL,yangw1234/BigDL,intel-analytics/BigDL