Support for None Secrets Provider for ToolHive in Kubernetes

[ChrisJBurns]

As described by @danbarr in issue#541. The thv CLI attempts to initialize the default encrypted secrets provider and prompts you interactively to set a password, which bombs out the container with an error.

We should add support for a none secret provider so that ToolHive inside of Kubernetes does not prompt you for any passwords. This is largely because the secrets themselves will be provided as env vars (with future support for file mounts), so we do not need to set a secrets provider.

There is also a point where we may want to support a kubernetes provider that forces thv to read straight from a specific secret instead of an environment variable, but for now we can just add the none provider.