Reduce SQL queries performed by GraphQL resolvers

[Mark90]

To resolve #351 this PR:

• Makes almost all GraphQL resolvers (except subscriptions) use the GQL query structure to derive the required SQLAlchemy query loaders to pass to .options()
• Patches strawberry's pydantic conversion to not load the data unless requested (n+1 problem)
• Changes several list fields in strawberry types to resolvers (n+1 problem)

Other notable changes:

• Cleanup SQLAlchemy models
• Add strawberry StatsExtension and PyInstrumentExtension that can be enabled through env-var (described in docs)
• Make it possible to log all SQLAlchemy queries (described in docs)

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 94.27711% with 19 lines in your changes missing coverage. Please review.

Project coverage is 83.36%. Comparing base (303a122) to head (76a2005).

Files	Patch %	Lines
orchestrator/graphql/schema.py	71.42%	2 Missing and 2 partials :warning:
orchestrator/app.py	66.66%	1 Missing and 1 partial :warning:
orchestrator/db/loaders.py	97.29%	1 Missing and 1 partial :warning:
orchestrator/graphql/extensions/stats.py	93.75%	1 Missing and 1 partial :warning:
orchestrator/graphql/schemas/helpers.py	71.42%	1 Missing and 1 partial :warning:
orchestrator/graphql/schemas/resource_type.py	50.00%	2 Missing :warning:
orchestrator/graphql/schemas/subscription.py	71.42%	2 Missing :warning:
orchestrator/graphql/utils/get_query_loaders.py	94.28%	0 Missing and 2 partials :warning:
orchestrator/graphql/utils/get_selected_paths.py	95.00%	0 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #716 +/- ## ========================================== + Coverage 83.01% 83.36% +0.34% ========================================== Files 181 188 +7 Lines 8962 9244 +282 Branches 1466 1509 +43 ========================================== + Hits 7440 7706 +266 - Misses 1265 1273 +8 - Partials 257 265 +8 ```

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