Fixed jobs create command to only accept JSON payload

[andrewnester]

Changes

Fixed jobs create command to only accept JSON payload.

Note: relies on this PR from Go SDK
databricks/databricks-sdk-go#522

Tests

andrew.nester@HFW9Y94129 cli % ./cli jobs create -h
Create a new job.

  Create a new job.

Usage:
  databricks jobs create [flags]

Flags:
  -h, --help        help for create
      --json JSON   either inline JSON string or @path/to/file.json with request body (default JSON (0 bytes))

Global Flags:
  -e, --environment string       bundle environment to use (if applicable)
      --log-file file            file to write logs to (default stderr)
      --log-format type          log output format (text or json) (default text)
      --log-level format         log level (default disabled)
  -o, --output type              output type: text or json (default text)
  -p, --profile string           ~/.databrickscfg profile
      --progress-format format   format for progress logs (append, inplace, json) (default default)