Add Array Node Index To current_context [Core feature]

### Motivation: Why do you think this is important?

In many cases, the index of array node in map tasks is needed, especially if the task is programmed to output a file with a static name that will be overwritten by subsequent array nodes. the index will help add a good name to that file for example and can be backtraced.

### Goal: What should the final outcome look like, ideally?

In the returned current_context() value, a filed of node_index or a good name should be there representing the map_task index.

### Describe alternatives you've considered

I generated a random id for each instance to distinguish which output came from which node.

### Propose: Link/Inline OR Additional context

_No response_

### Are you sure this issue hasn't been raised already?

- [X] Yes

### Have you read the Code of Conduct?

- [X] Yes