Add VpcConfig property for lambda functions in lambda_helper

[Guslington]

No description provided.

[toshke]

There will be 3 supported modes

1. for out-of-the-box functionality auto will be supported as vpc property value for lambda config
2. for fine-tuning, and providing other than compute subnets, following format shall be used:
3. Tweak of the previous mode

# Example1:  Pull Subnets from VPC Component automatically
lambdas:
  function1:
     vpc: auto

# Example2: Define your own security groups
lambdas:
  function1:
     vpc:
        subnets: <SUBNETDEFINITIONHERE>
        secgroups: <SECURITYGROUPSDEFINITIONHERE>

# Example3: Define security groups on group of functions
lambdas:
  vpc: auto  | example2 above
  functions:
    func1:
     ...
    func2:

@aaronwalker @Guslington let me know what you think on the format

[toshke]

If auto mode is used, component rendering lambdas will need to have dependency on vpc (that is, az_conditional_resources function defined.

[toshke]

@Guslington @aaronwalker implementation for auto behaviour can be found on feature branch on my fork

Instructions for testing can be found at https://github.com/toshke/hl-component-vpc-lambdas

[Guslington]

@toshke what about passing around the subnets using List<AWS::EC2::Subnet::Id> ? I'm going to do some testing with this in other components to see if we can drop the dependency of the vpc component.