{Util} Add util module for version and rest

[jiasli]

Description

Peel off az version and az rest from resource module. A new module util is created. Thus they don't carry the burden of

1. azure-mgmt-resource initialization when running these commands
2. scenario tests on resource command module when developing these commands

This makes running and developing az version and az rest significantly faster.

Testing Guide

> az version
{
  "azure-cli": "2.6.0",
  "azure-cli-command-modules-nspkg": "2.0.3",
  "azure-cli-core": "2.6.0",
  "azure-cli-dev-tools": "0.1.1",
  "azure-cli-nspkg": "3.0.4",
  "azure-cli-telemetry": "1.0.4",
  "azure-cli-testsdk": "0.2.4",
  "extensions": {
    "application-insights": "0.1.1",
    "interactive": "0.4.4",
    "mesh": "0.10.6",
    "timeseriesinsights": "0.1.2",
    "webapp": "0.2.24"
  }
}

> az rest -m GET -u https://management.azure.com/subscriptions/0b1f6471-1bf0-4dda-aec3-cb9272f09590/resourcegroups/rg1?api-version=2019-07-01
{
  "id": "/subscriptions/0b1f6471-1bf0-4dda-aec3-cb9272f09590/resourceGroups/rg1",
  "location": "westus",
  "name": "rg1",
  "properties": {
    "provisioningState": "Succeeded"
  },
  "tags": {
    "StorageType": "Standard_LRS",
    "type": "test"
  },
  "type": "Microsoft.Resources/resourceGroups"
}

[yonzhan]

add to S171

[zhoxing-ms]

We don't support Python 2.0+ anymore, right?
Do we still need from __future__ import print_function? print-as-a-function

[jiasli]

Nice catch! I simply migrated the code from src/azure-cli/azure/cli/command_modules/resource/custom.py. Removed.

[zhoxing-ms]

LGTM

[Juliehzl]

Prefer to not use print() according to command guideline.