Allow BuildConfig to add Linux capabilities

1. Proposed title of this feature request

• Allow BuildConfig to add Linux capabilities

2. What is the nature and description of the request?

• When creating a Pod there is the ability to add Linux capabilities via spec.securityContext.capabilities.add.  However, there is no method to add these capabilities for BuildConfig.  

3. Why does the customer need this? (List the business requirements here)

• This can be useful in certain circumstances, like the new CHECKPOINT_RESTORE for certain applications, including Java.  
•  Would be useful to allow to build and run on OCP without needing a different CI/CD pipeline.

4. List any affected packages or components.