Specify security context in the devfile before generating the kubernetes resources

As part of Ensure users don't have root access in containe... (#396300 - closed) , we want to explicitly set the security context of the kubernetes resources being generated.

Devfile library allows specifying these parameters through pod-overrides and container-overrides attributes. However, https://github.com/devfile/library/pull/158 which is implementing this feature is not part of v2.2.0 which is the latest release of the devfile which is being used in the devfile-gem.

Once devfile library releases a new version, update the devfile-gem and move the logic of setting the security context in the devfile_processor as part of workspace creation.