datastore: update postgres package

[hdonnay]

These changes are the result of trying to go through and apply a uniform style to the datastore/postgres package.

TODO

• metrics pass
• coverage pass -- Need to audit the span names
• preamble/boilerplate pass
• move ctxlock/v2 to a locksource hierarchy?
• split the "implement" giant commit (started)
• undo use of the slices package
• downgrade the otel packages to 1.18 (for Clair reasons -- it needs Jaeger export support) (It works just fine to have Clair carry the Jaeger requirement and make MVS do the work.)
• Implement the delta interface

[codecov]

Codecov Report

Attention: Patch coverage is 66.67845% with 943 lines in your changes are missing coverage. Please review.

Project coverage is 54.32%. Comparing base (b28ae8c) to head (a2c16b0).

❗ Current head a2c16b0 differs from pull request most recent head 123b1f6. Consider uploading reports for the commit 123b1f6 to get more accurate results

Files	Patch %	Lines
...atastore/postgres/v2/matcher_v1_updateoperation.go	49.16%	108 Missing and 14 partials ⚠️
datastore/postgres/v2/matcher_v1_enrichment.go	0.00%	110 Missing ⚠️
...atastore/postgres/v2/matcher_v1_vulnerabilities.go	70.85%	87 Missing and 15 partials ⚠️
locksource/pglock/pglock.go	63.52%	81 Missing and 12 partials ⚠️
datastore/postgres/v2/common.go	71.11%	60 Missing and 18 partials ⚠️
datastore/postgres/v2/indexer_v1_manifest.go	57.25%	38 Missing and 15 partials ⚠️
datastore/postgres/v2/indexer_v1_index.go	74.50%	42 Missing and 9 partials ⚠️
datastore/postgres/v2/matcher_v1.go	38.27%	43 Missing and 7 partials ⚠️
...astore/postgres/v2/indexer_v1_affectedmanifests.go	75.50%	38 Missing and 11 partials ⚠️
datastore/postgres/v2/metrics.go	76.96%	34 Missing and 4 partials ⚠️
... and 14 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1092      +/-   ##
==========================================
- Coverage   55.79%   54.32%   -1.48%     
==========================================
  Files         265      249      -16     
  Lines       16552    19713    +3161     
==========================================
+ Hits         9236    10709    +1473     
- Misses       6357     8043    +1686     
- Partials      959      961       +2     

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[hdonnay]

@crozzy regarding the big-boy "add new package" commit: any opinion on how to split it up? I was thinking the common code and associated tests in a few commits, then the matcher and indexer implementations and tests in separate commits.

[hdonnay]

I think is is good to get reviewed. I think the tests need a later pass to work through the Sequence Scan test.