Alternative CLI output formats

[bnichell]

Currently the output format is human readable.
For automation purposes, I propose to introduce further output formats, which then could be e.g. used in CI pipelines.
abaplint provides several formats for this purpose.
Interesting for my use case, would be the checkstyle and/or junit format.
The junit format is documented here.

For both mentioned formats it is important to ensure that no characters are in the messages that are incompatible to the XML format (replace < with < and > with >) ¹.

Footnotes

1. Relevant abaplint correction to replace unsupported characters: https://github.com/abaplint/abaplint/pull/3251/commits/63d08dd6cadf30ab8b4859e7867cabdc63803bfe#diff-1efa14c10eed3c319bc557ee12afdb8e920ad0aca9465520b3240b5032a89780. ↩