Tweak STAC link handling

[Ariana-B]

Reason for this pull request

Tweak how STAC links are provided/determined, and include Sat and Sar extension links in stac_extensions when present.
Also take the opportunity to add a test for s1_nrb data.

Proposed changes

• Rename stac_url to base_url for better clarity, as the url is not expected to include /stac

• Remove collection_url param as it seems to be unnecessary

• Don't use dataset uri to determine self and odc_yaml links, and warn if self link cannot be determined

• Bring back dataset_location parameter from the original eo-datasets implementation, but rename to asset_location to be more accurate to its usage

• Closes #xxxx

• Tests added / passed

• Pull Request Title will make sense in ODC Release Notes

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📚 Documentation preview 📚: https://opendatacube--2156.org.readthedocs.build/en/2156/

[SpacemanPaul]

One potential optimisation, and we need to get that test passing one way or another, as discussed.

[codecov]

Codecov Report

❌ Patch coverage is 95.65217% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 86.39%. Comparing base (fa888a1) to head (b9c6d76).
⚠️ Report is 5 commits behind head on develop.

Files with missing lines	Patch %	Lines
datacube/metadata/_stacconverter.py	95.65%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #2156   +/-   ##
========================================
  Coverage    86.38%   86.39%           
========================================
  Files          151      151           
  Lines        16377    16382    +5     
========================================
+ Hits         14148    14153    +5     
  Misses        2229     2229           

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