Allow disabling color

[jiasli]

Fixes #170, #169. Also reported in Azure/azure-cli#6080 and causes side effect of Azure/azure-cli#9903.

If stdout is redirected and CLI displays a colored output, the color in the console can't revert back to the default because Colorama only resets color in stdout, but not stderr (tracked at tartley/colorama#200, tartley/colorama#218). This is affecting pip as well: pypa/pip#6354 and pip uses --no-color to disable coloring pypa/pip#4739. Azure CLI will add this option too.

Without proper a fix from Colorama, Knack can now

• Disable color via {CLI}_CORE_NO_COLOR environment variable.
• Use config

  [core]
  no_color=True
  

The PR removes Colorma from

1. output: output.py which replaces out_file with a Colorma stream and generates colorized output like jsonc
2. log: log.py which replaces self.stream with a Colorma stream and generates colorized logs
3. help: help.py which initializes Colorama for help message
4. deprecation/preview warning: invocation.py which initializes Colorama for deprecation and preview warning messages and util.py which generates colorized warning for StatusTag

self.stream.isatty() is removed because Colorama has its own mechanism to detect tty and treat PyCharm as a tty: https://github.com/tartley/colorama/blob/405b982f39efeaf697d3e2a6b90f9b913b38e97d/colorama/ansitowin32.py#L45

To test,

1. Clone Knack to the local machine
2. Pull from my branch
3. Activate the virtual env of Azure CLI and run

pip install --editable <path_to_knack>

# disable color
# cmd
set {CLI}_CORE_NO_COLOR=1
# bash
export {CLI}_CORE_NO_COLOR=1
# pwsh
$Env:{CLI}_CORE_NO_COLOR=1

# enable color
set {CLI}_CORE_NO_COLOR=

# test output color
az vm list --output jsonc

# test log color
az vm list --debug

# test help color
az vm create -h

# test deprecation warning color
az vm image accept-terms

[Juliehzl]

@jiasli Should we consider upgrading knack version for the change?

[jiasli]

Yes. But let's test it first. We will bump the version when other PRs are merged.

[yungezz]

the change will disable color output from az cli totally?

[jiasli]

Yes, Colorama won't be initialized with KNACK_NO_COLOR set to 1.

[jsntcy]

• So if the user need disable color, does he/she need call 'set KNACK_NO_COLOR=1'?
• If user 'set KNACK_NO_COLOR=1'. is the behavior compatible as before for correct scenarios?

[jiasli]

The user can either call set KNACK_NO_COLOR=1 or set environment variable for the user or the system.

If the user runs set KNACK_NO_COLOR=1, only color is disabled with no change in the behavior, except that warnings will be prefixed with the level as a substitution for coloring, like ERROR for red 🟥, WARNING for yellow 🟨, INFO for green 🟩 and DEBUG for blue 🟦.