feat: Enhance Pipeline.__repr__()

[silvanocerza]

Related Issues

• fixes Pipeline.__repr__ should display an easy to understand representation of the Pipeline #6803

Proposed Changes:

Adds a custom __repr__ method in Pipeline that returns a nice text representation of a Pipeline.
If ran in a Jupyter notebook, like when it's the last statement of a cell, it will instead display the image created with Pipeline.draw().

pipe = Pipeline(metadata={"test": "test"}, max_loops_allowed=42)
pipe.add_component("add_two", AddFixedValue(add=2))
pipe.add_component("add_default", AddFixedValue())
pipe.add_component("double", Double())
pipe.connect("add_two", "double")
pipe.connect("double", "add_default")

Would generate this output:

<haystack.core.pipeline.pipeline.Pipeline object at 0x1490c81f0>
🧱 Metadata
  - test: test
🚅 Components
  - add_two: AddFixedValue
  - add_default: AddFixedValue
  - double: Double
🛤️ Connections
  - add_two.result -> double.value (int)
  - double.value -> add_default.value (int)

How did you test it?

I added new unit tests.

Notes for the reviewer

Depends on #6961.

Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test:.
• I documented my code
• I ran pre-commit hooks and fixed any issue

[shadeMe]

LGTM! You might want to remove the generated PNG files from the PR before merging, though.