feat(MRS): add new resources

[kolsean]

This PR add 2 objects:

Resources
sbercloud_mapreduce_cluster
sbercloud_mapreduce_job

This closes #67

All acceptance tests are done:

==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./sbercloud -v -run TestAccMrsMapReduce -timeout 360m -parallel=1
=== RUN   TestAccMrsMapReduceCluster_basic
=== PAUSE TestAccMrsMapReduceCluster_basic
=== RUN   TestAccMrsMapReduceJob_basic
=== PAUSE TestAccMrsMapReduceJob_basic
=== CONT  TestAccMrsMapReduceCluster_basic
--- PASS: TestAccMrsMapReduceCluster_basic (814.26s)
=== CONT  TestAccMrsMapReduceJob_basic
--- PASS: TestAccMrsMapReduceJob_basic (1130.63s)
PASS
ok      github.com/sbercloud-terraform/terraform-provider-sbercloud/sbercloud   1945.612s