[CONTP-951] Support env vars passed down to dd logging container

[Mathew-Estafanous]

What does this PR do?

Motivation

A customer requested the ability to configure log router level environment variables in addition to the datadog agent. Currently, only the agent can be configured with dd_environment so this PR adds a similar option to dd_log_collection

Describe how you validated your changes

1. Updated logging_only_test.go test to validate env vars passed to dd_log_collection.fluentbit_config.environment are passed down to the container task def.

2. Manually QAd by provisioning an ecs fargate task with an added environment var in the dd_log_collection then confirmed the env var is found in the task def on aws console.

Manual test results

Config:

AWS Console

Additional Notes

[gabedos]

Looks good to me!

Thanks for making the task_family_name a configurable variable. You must've run into some conflicts when I also had the same resources generated in the same account.

[gabedos]

#33