feat: add clientless LocalStack service

[cofin]

Summary\n\n- add a LocalStack SQS service using awslocal or the bundled aws CLI inside the container\n- support shared worker prefixes and per-worker server isolation\n- document image overrides and register one-provider selective CI ownership\n\n## Validation\n\n- provider tests: 5 passed\n- Ruff, mypy, pyright, and docs passed\n- selector: 1 provider job, 1 image pull\n- no boto3, Python client dependency, or lockfile change\n\nPart of #150.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 101 lines in your changes missing coverage. Please review.
✅ Project coverage is 1.32%. Comparing base (ba9c758) to head (b8b036e).

Files with missing lines	Patch %	Lines
src/pytest_databases/docker/localstack.py	0.00%	101 Missing ⚠️

Additional details and impacted files

@@                   Coverage Diff                   @@
##           feat/podman-support    #156       +/-   ##
=======================================================
- Coverage                11.95%   1.32%   -10.64%     
=======================================================
  Files                       24      25        +1     
  Lines                     2082    2183      +101     
  Branches                   169     182       +13     
=======================================================
- Hits                       249      29      -220     
- Misses                    1798    2154      +356     
+ Partials                    35       0       -35     

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[Nahuel990]

Why not MiniStack? https://ministack.org