Add declarative execution environment management to rstudio-connect chart

[lucasrod16]

Summary

• Adds executionEnvironments values key for declarative management of execution environments via ExecutionEnvironments.ConfigFilePath.
• Unlike launcher.customRuntimeYaml, changes take effect on every helm upgrade without requiring a pod restart or database reset.
• The ConfigMap is deliberately excluded from checksum annotations so the kubelet can update the mounted file in-place.

Test plan

• just test rstudio-connect — 31 unit tests pass
• helm lint --strict with execution environments values
• helm template renders correct ConfigMap, volume, volumeMount, and gcfg config
• Deploy to a test cluster and run helm test to verify end-to-end

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