Introduce merge to methods for profiles

[iblancasa]

Continuation #13106

• Added Profiles.MergeTo implementation that merges one profile message into another while reconciling their dictionaries and appending
  resource profiles.
  • Added comprehensive unit tests covering both the successful merge path and error propagation when dictionary switching fails.

Merge after #14075

[codecov]

Codecov Report

❌ Patch coverage is 74.66063% with 56 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.18%. Comparing base (0f3b0c9) to head (af0278d).
⚠️ Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
pdata/pprofile/location.go	64.28%	5 Missing and 5 partials ⚠️
pdata/pprofile/profile.go	66.66%	5 Missing and 5 partials ⚠️
pdata/pprofile/sample.go	74.19%	4 Missing and 4 partials ⚠️
pdata/pprofile/function.go	73.91%	3 Missing and 3 partials ⚠️
pdata/pprofile/mapping.go	70.00%	3 Missing and 3 partials ⚠️
pdata/pprofile/keyvalueandunit.go	75.00%	2 Missing and 2 partials ⚠️
pdata/pprofile/line.go	69.23%	2 Missing and 2 partials ⚠️
pdata/pprofile/valuetype.go	75.00%	2 Missing and 2 partials ⚠️
pdata/pprofile/profiles_merge.go	84.61%	1 Missing and 1 partial ⚠️
pdata/pprofile/stack.go	84.61%	1 Missing and 1 partial ⚠️

❌ Your patch check has failed because the patch coverage (74.66%) is below the target coverage (95.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #14091      +/-   ##
==========================================
- Coverage   92.50%   92.18%   -0.32%     
==========================================
  Files         660      663       +3     
  Lines       36196    41314    +5118     
==========================================
+ Hits        33483    38087    +4604     
- Misses       1892     2200     +308     
- Partials      821     1027     +206     

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