Add xml and json output format

[arekzaluski]

Why

It is very difficult to parse existing txt output. Addition of xml and json will allow the output to be easily parsable by other tools/extensions.

Changes

• Add xml and json option to format output
  It will print events and event statistics as xml/json file or on stdout.

Example:

eventlist -f json -o output.json <logFile>

[JonatanAntoni]

@arekzaluski, could you address the lint warnings, please?

[arekzaluski]

@JonatanAntoni @bgn42 I've fixed linting issues and added tests for xml and json. It's ready to be rechecked.

[codecov-commenter]

Codecov Report

Merging #33 (d8b2ef4) into main (224c8c4) will increase coverage by 0.06%.
The diff coverage is 95.00%.

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@@            Coverage Diff             @@
##             main      #33      +/-   ##
==========================================
+ Coverage   96.77%   96.84%   +0.06%     
==========================================
  Files           9        9              
  Lines        3321     3389      +68     
==========================================
+ Hits         3214     3282      +68     
- Misses         73       74       +1     
+ Partials       34       33       -1     

Impacted Files	Coverage Δ
tools/eventlist/pkg/output/output.go	89.53% <94.87%> (+1.67%)	⬆️
tools/eventlist/cmd/eventlist/main.go	97.52% <100.00%> (+0.04%)	⬆️

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[bgn42]

Looks very good now.