loggingexporter: add support for AttributeMap

[sumo-drosiek]

Description:

Add printing map to logging exporter.
Currently maps are printed as <Unknown OpenTelemetry attribute value type MAP>. An idea of the PR is to put it in more usable form. Nested maps are stringified jsons

Example output:

Some text: {
     -> foo: STRING(test)
     -> zoo: MAP({"bar":13})
}

Testing:
unit tests

[codecov]

Codecov Report

Merging #2609 (df01246) into main (bf8b945) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #2609   +/-   ##
=======================================
  Coverage   92.02%   92.02%           
=======================================
  Files         271      271           
  Lines       15446    15455    +9     
=======================================
+ Hits        14214    14223    +9     
  Misses        850      850           
  Partials      382      382           

Impacted Files	Coverage Δ
exporter/loggingexporter/logging_exporter.go	96.40% <100.00%> (+0.12%)	⬆️

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