Tighten up values schema for bb-common

Various objects within the values schema for bb-common are missing additionalProperties: false, which prevents any properties that are not specified in the schema to be accepted.

An easy example would be the top level property networkPolicies, which enumerates the possible keys in the schema but still accepts arbitrary additional keys:

# this works today
$ helm template chart --set=networkPolicies.foo=bar 

Adding additionalProperties: false to the top level networkPolicies key would end up looking like this:

# should explode
$ helm template chart --set=networkPolicies.foo=bar
Error: values don't meet the specifications of the schema(s) in the following chart(s):
bb-common:
- networkPolicies: Additional property foo is not allowed

I believe at a minimum we should ensure the following have additionalProperties: false

• .networkPolicies
• .networkPolicies.egress
• .networkPolicies.ingress
• .networkPolicies.egress.defaults
• .networkPolicies.ingress.defaults