feat: add support to dynamic header on legacy config

[bozzelliandrea]

Which problem is this PR solving?

Follow up of pr: #5179 , introducing dynamic header support also for legacy base config, to be albe to use it also for logs/traces/metrics exporters which extends OTLPExporterNodeBase class.

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Tested with locally instrumentation over nodejs and nextjs applications

Checklist:

• Followed the style guidelines of this project
• Unit tests have been added
• Documentation has been updated

[linux-foundation-easycla]

• ❌ - login: @bozzelliandrea / name: Andrea Bozzelli . The commit (a125882) is not authorized under a signed CLA. Please click here to be authorized. For further assistance with EasyCLA, please submit a support request ticket.

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 1 line in your changes missing coverage. Please review.

Project coverage is 94.58%. Comparing base (fc94e46) to head (a125882).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...ter-base/src/configuration/shared-configuration.ts	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5221      +/-   ##
==========================================
- Coverage   94.60%   94.58%   -0.03%     
==========================================
  Files         315      315              
  Lines        8012     8014       +2     
  Branches     1617     1618       +1     
==========================================
  Hits         7580     7580              
- Misses        432      434       +2     

Files with missing lines	Coverage Δ
...ter-base/src/configuration/shared-configuration.ts	96.42% <66.66%> (-3.58%)	⬇️

... and 1 file with indirect coverage changes