otelzap: Implement namespace method

[khushijain21]

Part of #5191

Pre-work #5279

The approach is to use linked list to open a namespace and keep track of it.
calculate method iterates to the most nested namespace and appends data in reverse order.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 64.5%. Comparing base (c7fb822) to head (340b6e6).

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #5721   +/-   ##
=====================================
  Coverage   64.4%   64.5%           
=====================================
  Files        200     200           
  Lines      12540   12557   +17     
=====================================
+ Hits        8084    8100   +16     
  Misses      4220    4220           
- Partials     236     237    +1     

Files	Coverage Δ
bridges/otelzap/core.go	89.8% <100.0%> (+0.1%)	⬆️
bridges/otelzap/encoder.go	85.8% <100.0%> (+2.0%)	⬆️

... and 1 file with indirect coverage changes

[pellared]

build_and_test / lint (pull_request) is failing. Can you fix it before I make a review?