Allow for configuring default container/pod SecurityContext in CheCluster CR

[AObuchow]

Is your enhancement related to a problem? Please describe

Currently, there is no way to set the default pod security context or container security context used by workspaces from the Che Cluster CR.

if Che users want to configure the default pod security context or container security context used by workspaces, they have to modify the Che-owned DWOC and set the [corresponding fields](pod security context or container security context used by workspaces) there. However, Che-Operator will automatically configure the

Describe the solution you'd like

It'd be better to allow for configuring the default pod security context or container security context used by workspaces through the Che Cluster CR.

When the containerSecurityContext or podSecurityContext is configured in the Che Cluster CR, we have to make sure it doesn't have any problematic interactions with the container-build SCC if disableContainerBuildCapabilities is set to false (i.e. when container builds are enabled). For instance, it would be invalid to set allowPrivilegeEscalation: false through the containerSecurityContext when container builds are enabled.

IIRC:

Describe alternatives you've considered

The podSecurityContext field config.workspace.podSecurityContext can be set by user in the Che-owned DWOC to set a default pod security context to be used by workspaces. However, the Che-Operator will automatically configure the containerSecurityContext field config.workspace.containerSecurityContext, so there is no workaround for configuring the default workspace container security context.

Additional context

Downstream issue