Add `--json` flag

[soar]

This flag adds an ability to print JSON lines as formatted (and, optionally, highlighted) text. Supports --query and --color options.

Before:

awslogs get RDSOSMetrics instance-id --query '{engine: engine, uptime: uptime, processList: processList}'

After:

awslogs get RDSOSMetrics instance-id --query '{engine: engine, uptime: uptime, processList: processList}' --json

Updated to match the new code style. Conflicts fixed. The old version is still available in the fork here: https://github.com/soar/awslogs/tree/feature/pretty-json-legacy

[soar]

@jorgebastida Hello! I see activity in the repo, so I updated the branch. Review this, please.