Implement the Export method of the otlploghttp Exporter

[MrAlias]

Part of #5057

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.9%. Comparing base (b13ee4a) to head (1ef2fc8).

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #5182   +/-   ##
=====================================
  Coverage   83.9%   83.9%           
=====================================
  Files        255     256    +1     
  Lines      16596   16601    +5     
=====================================
+ Hits       13928   13938   +10     
+ Misses      2375    2370    -5     
  Partials     293     293           

Files	Coverage Δ
exporters/otlp/otlplog/otlploghttp/exporter.go	91.6% <100.0%> (+1.1%)	⬆️
...otlp/otlplog/otlploghttp/internal/transform/log.go	100.0% <100.0%> (ø)

... and 2 files with indirect coverage changes