feat(): add security context on the container level

[anja-istenic]

It is recommended practice to give a resource (pod/container) the least privileges it needs. The Lenses Helm Chart already supports configuring the security context on the pod level. This PR adds the securityContext configurations on the container level (more info on container level securityContext here).

This change is fully backwards compatible, as the containerSecurityContext value configuration is optional and defaults to {}

[anja-istenic]

@georgeyord Not sure what the merge process is but any review or feedback would be much appreciated.

[waewoo]

Hello

I am also interested in this feature (internal security rules...).
When is it expected that this MR be merged ?

Thanks

PS:
It will be necessary to add it in lenses-provision container too.