Add support for 'checkstyle' output

[sebastien-rosset]

Please check if the PR fulfills these requirements

• The commit message follows our guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features) see docs/README.md

What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

Add support for the checkstyle output format. Checkstyle is a static code analysis tool used in software development.

What is the current behavior? (You can also link to an open issue here)

Currently, woke supports the following output formats: text, simple, github-actions, json and sonarqube.

What is the new behavior (if this is a feature change)?

Adding new output format (checkstyle).

Does this PR introduce a breaking change? (What changes might users need to make due to this PR?)

No

Other information:

Checkstyle is a static code analysis tool used in software development. While checkstyle was originally designed for Java static analysis, multiple CICD tools support the checkstyle XML format. The checkstyle format can be used to report generic static analysis issues, not just Java. A list of supported tools is available at https://checkstyle.org/index.html#Related_Tools_Active_Tools

For example:

1. golangci-lint can produce output of golang static analysis in checkstyle format.
2. The Jenkins warning NG plug-in can show the results of static analysis using checkstyle format.

Though the checkstyle format is very simple, there is no formal XSD. See checkstyle/checkstyle#5166

[codecov]

Codecov Report

Merging #209 (da19863) into main (a6470c4) will decrease coverage by 0.72%.
The diff coverage is 78.37%.

❗ Current head da19863 differs from pull request most recent head 1623e27. Consider uploading reports for the commit 1623e27 to get more accurate results

@@            Coverage Diff             @@
##             main     #209      +/-   ##
==========================================
- Coverage   94.49%   93.76%   -0.73%     
==========================================
  Files          22       23       +1     
  Lines         781      818      +37     
==========================================
+ Hits          738      767      +29     
- Misses         25       30       +5     
- Partials       18       21       +3     

Impacted Files	Coverage Δ
pkg/printer/checkstyle.go	77.14% <77.14%> (ø)
pkg/printer/printer.go	100.00% <100.00%> (ø)

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[caitlinelfring]

One last comment, otherwise LGTM

[caitlinelfring]

I'm not a fan of using panic as it's not the best user experience, but Start doesn't return an error so that's more of an issue for the interface and not for what implements it. Nothing for you to do here but just felt like commenting on it.

[sebastien-rosset]

Yes, I agree. I wanted to be able to return an error and not silently ignore the problem. Maybe in a future PR the signature of the function can change to return an error.

[sebastien-rosset]

Thanks!

[caitlinelfring]

Released in v0.19.0