Make configuration more flexible by adding the FARGATE_TASK variable
We should introduce a FARGATE_TASK
environment variable (in the driver it would be available as CUSTOM_ENV_FARGATE_TASK
).
The driver should check for the presence of such variable, and if it's available, its content should be set as the task identifier - instead of the default defined in the configuration file.
This would allow to use multiple pre-defined tasks with one Runner with the Fargate driver. Instead of a need of registering a new one for each task that we would like to use.