Addresses Issue 81 -- Adds support for container-level security contexts

[trhynard]

Proposed changes

This PR adds support for container-level security contexts in the Deepgram Self-Hosted Helm chart, addressing issue #81. Previously, the chart only supported pod-level security contexts, which limited security configuration granularity.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update or tests (if none of the other choices apply)

Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your code.

• I have read the CONTRIBUTING doc
• I have tested my changes in my local self-hosted environment
  • I used this chart to install Deepgram in our non-prod k8s cluster, verified correct deployment config and that the application operates correctly
• I have added necessary documentation (if appropriate)

Further comments

New functionality:

• Container-level security contexts allow for more fine-grained security control, essential for enterprise deployments
• Enables different security settings for containers within the same pod
• Supports advanced security features like capability dropping, seccomp profiles, and privilege escalation controls

The implementation follows existing chart patterns and maintains full backward compatibility. All existing securityContext configurations will continue to work unchanged.