Allow agent-specific resources or using environment variables in resource names (in UI config & Job DSL)

Creating the config via UI or Job DSL, it's not possible to refer to environment variables.

We're running multiple agents, and if a port (like 8080) gets reserved in one agent, it shouldn't block builds on other agent.

To tackle this, I'm using `NODE_NAME` environment variable in pipeline scripts, e.g.:

```groovy
lock("${env.NODE_NAME}-port-8080") {
...
}
```

That works.

Unfortunately, what doesn't work, is if you attempt to do that same in non-pipeline setup:


This doesn't evaluate the environment variable in the build time, and the locked name remains as literal `${NODE_NAME}-port-8080`.

Two potential solutions:

1) Allow using environment names
2) Add a flag for resource to be declared as "agent-specific" (so that the resource can be reserved _per_-agent)