feat: add kong config with nginx_worker_processes option

[Wakeful-Cloud]

What kind of change does this PR introduce?

This PR adds the ability to configure Kong's nginx_worker_processes value via the below TOML config:

[kong]
# Number of Nginx workers. Set this to 1 to minimize memory usage.
nginx_worker_processes = 1

What is the current behavior?

When running in memory-constrained environments, Kong/Nginx may spawn an excessive number of workers, drastically increasing memory usage.

What is the new behavior?

This PR allows users to fine-tune the number of Kong/Nginx worker processes when desired. If no configuration is provided, the previous behavior (auto) is used.

Additional context

For my use case, this allowed me to cut memory usage of the entire Supabase Docker compose by 79%! (1487 MiB -> 312 MiB) by setting it to just 1 (I'm not especially concerned about the reduced routing performance).

[coveralls]

Pull Request Test Coverage Report for Build 5434097181

• 16 of 16 (100.0%) changed or added relevant lines in 1 file are covered.
• 7 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.04%) to 62.014%

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Files with Coverage Reduction	New Missed Lines	%
internal/gen/keys/keys.go	7	7.94%

Totals
Change from base Build 5431792736:	-0.04%
Covered Lines:	4674
Relevant Lines:	7537

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💛 - Coveralls

[sweatybridge]

This is great change! I think it's safe to default to 1 for local development.