feat(resources): use functions over constants for default and empty resources

[pichlermarc]

Which problem is this PR solving?

My suggestion from #5421 (comment) - using functions over constants to create an empty or default resource, aligning with the other factory function resourceFromAttributes

Fixes # (issue)

Type of change

• Breaking change (fix or feature that would cause existing functionality to not work as expected)

How Has This Been Tested?

• Unit tests

[codecov]

Codecov Report

Attention: Patch coverage is 81.25000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 94.94%. Comparing base (1a5b57b) to head (d1fe6f6).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...ntelemetry-browser-detector/src/BrowserDetector.ts	0.00%	2 Missing ⚠️
...es/opentelemetry-resources/src/detect-resources.ts	50.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5467   +/-   ##
=======================================
  Coverage   94.94%   94.94%           
=======================================
  Files         309      309           
  Lines        8017     8019    +2     
  Branches     1701     1701           
=======================================
+ Hits         7612     7614    +2     
  Misses        405      405           

Files with missing lines	Coverage Δ
...imental/packages/opentelemetry-sdk-node/src/sdk.ts	96.01% <100.00%> (ø)
...perimental/packages/sdk-logs/src/LoggerProvider.ts	97.77% <100.00%> (ø)
...es/shim-opencensus/src/OpenCensusMetricProducer.ts	100.00% <100.00%> (ø)
...ckages/opentelemetry-resources/src/ResourceImpl.ts	98.33% <100.00%> (+0.05%)	⬆️
...elemetry-sdk-trace-base/src/BasicTracerProvider.ts	95.58% <100.00%> (ø)
packages/sdk-metrics/src/MeterProvider.ts	100.00% <100.00%> (ø)
...es/opentelemetry-resources/src/detect-resources.ts	85.00% <50.00%> (ø)
...ntelemetry-browser-detector/src/BrowserDetector.ts	13.33% <0.00%> (ø)