Add support for colorized output

[acc-jon]

Add a command-line option to specify whether output should be colored (default="auto"). In auto mode, colors will be enabled if the output will be written to a terminal. The coloring is applied after the output has been marshalled, to avoid corrupting any output data. Add --use-colors=false to force colors off.

Note that coloring is only applied to JSON and YAML output, because coloring XML is not helpful. XML is already too dense to read easily.

Default colors are built in, but are user configurable via a JSON file. Example in pkg/termcolor/color_patterns.json.sample. Enable the custom colors with an environment variable, TERRASCAN_COLORS_FILE=<absolute-path-to-color_patterns.json>

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
0 Vulnerabilities (and 0 Security Hotspots to review)
1 Code Smell

No Coverage information
0.0% Duplication

[codecov]

Codecov Report

Merging #347 into master will increase coverage by 0.59%.
The diff coverage is 57.61%.

@@            Coverage Diff             @@
##           master     #347      +/-   ##
==========================================
+ Coverage   61.45%   62.05%   +0.59%     
==========================================
  Files          57       61       +4     
  Lines        1069     1215     +146     
==========================================
+ Hits          657      754      +97     
- Misses        346      391      +45     
- Partials       66       70       +4     

Impacted Files	Coverage Δ
pkg/cli/output_writer.go	0.00% <0.00%> (ø)
pkg/cli/scan.go	31.25% <5.00%> (-33.04%)	⬇️
pkg/cli/run.go	33.33% <25.00%> (-2.39%)	⬇️
pkg/termcolor/colorpatterns.go	40.47% <40.47%> (ø)
pkg/termcolor/termcolor.go	80.00% <80.00%> (ø)
pkg/termcolor/writer.go	100.00% <100.00%> (ø)
... and 4 more

[cesar-rodriguez]

Thanks!