CLOUDP-73724: mongocli ops-manager admin backup fileSystem(s) describe

[andreaangiolillo]

Proposed changes

Jira ticket: CLOUDP-73724

Checklist

• I have signed the MongoDB CLA
• I have added tests that prove my fix is effective or that my feature works
• I have added any necessary documentation (if appropriate)
• I have run make fmt and formatted my code

Further comments

./bin/mongocli om admin backup filesystem describe test -P ops
ID     PATH   WT COMPRESSION   MMAPV1 COMPRESSION
test   /      NONE             GZIP

./bin/mongocli om admin backup filesystem describe test -P ops -o json
{
  "id": "test",
  "loadFactor": 1,
  "mmapv1CompressionSetting": "GZIP",
  "storePath": "/",
  "wtCompressionSetting": "NONE",
  "assignmentEnabled": true
}

[gssbzn]

LGTM