feat(AWS Lambda): Support loggingConfig

[ryy]

Closes: #12264

[darcoli]

By default, Serverless also provisions the Log Group itself as part of it's cloudformation stack. At that stage, the custom log group name also needs to be checked.

[darcoli]

I think this could be more compact as:

if (functionObject.loggingConfig) {
  const loggingConfig = {};

  ({
    ApplicationLogLevel: loggingConfig.applicationLogLevel,
    LogFormat: loggingConfig.logFormat,
    LogGroup: loggingConfig.logGroup,
    SystemLogLevel: loggingConfig.systemLogLevel,
  } = functionObject.loggingConfig);

  functionResource.Properties.LoggingConfig = Object.keys(loggingConfig).length ? loggingConfig : undefined;
}

[tusharf5]

would this also allow to set this config at a global level so it's applied to all lambdas?