feat: enhance string interpolation with nested accessors support

[tortolero-ruben]

This PR adds support for dictionaries and lists as variables.

Changes:

• expanded the regex pattern to capture dictionaries and lists
• added helper function to handle chained accessors like list_of_dictionaries[0].first_key
• comments to make explain the flow

[lucasgomide]

drop this comment pls

[lucasgomide]

@tortolero-ruben do you mind to share a real case that it address?

[tortolero-ruben]

@tortolero-ruben do you mind to share a real case that it address?

No problem.

I have a task that I'm defining like:

description:
  <inputs>
    <documentation>
      {documentation[0].context_for_this_task}
    </documentation>
    <examples>
      <example1>{documentation[0].example}</example1>
      <example2>{documentation[1].example}</example2>
    </examples>
  </inputs>

Where documentation is a list of dictionaries/pydantic objects containing, in my case documentation and different types of examples for the flow. However, not all documentation and examples are needed for all tasks. Some tasks only need some of the documentation or some examples. So being able to pass a "container" variable like documentation and access the items it's pretty nice.

I understand I could simply define more variables and pass values to those but that becomes burdensome if I have a lot of variables.