Make results compatible to MLPerf submission checker for 6.0

[tanvi-mlcommons]

Submission checker for inference requires the result to be in certain format to be validated.

1. Publish a minimal schema for 6.0 validation that endpoints must follow
2. Create a thin translation layer that:
   a. Takes endpoint output (primarily JSON right now but we should keep this open to any format)
   b. Converts it into the format the submission checker expects

[nvzhihanj]

Closing as superseded by #79. This issue tracked MLPerf submission compatibility specifically for version 6.0. #79 is the broader, general tracking issue for MLPerf submission compatibility and supersedes this version-specific one. Context from this issue has been preserved on #79.