🚀[FEATURE]: Iterate operator

[BenRacicot]

Relevant Package

This feature request is for @ngxs/store/operators

Description

Iterating on store data arrays does not have a dedicated operator.

• For dynamic data this is necessary where we don't have a target for updateItem.
• Recursion with NGXS state is a very common question from users.
• We should probably be using built-in operators over custom code in state files.

Describe the problem you are trying to solve

Various engineers have stated that there exists no NGXS operator to iterate an array.
This causes pain when updating nested data like the tasks arrays in the image above. I've had to write native JS for recursion and to update nested items.

Describe the solution you'd like

An iterate operator that allows us to run operators on each index of the data store.
This way we could execute an iif and subsequent operators (possible recursion) on each index.

ctx.setState(
  patch({
    board: patch({
      // iterate statuses, look for the key 'tasks', run an operator on this index
      statuses: iterate(
      	'tasks': iif( 
	    (tasks) => tasks?.some((task: any) => task.task_id === payload.task_id), // condition
	    updateItem<any>((task: any) => task.task_id === payload.task_id, props) // if true
	    // insertItem() // if false
      	),
      )
    }),
  })
);

Describe alternatives you've considered

Currently using native JS to update nested items.
Tried many variations of operators to make this happen and spoke to several members of the community.
Here is a Stackblitz with the problem all set up so solve (see @Action(UpdateTask))