feat: make git actions deterministic for fix_pipeline

What does this merge request do and why?

Previously, fix_pipeline used prompts to tell the Agent to add, commit, and push the code changes it has made. This MR changes these actions to be deterministic (i.e. we do not have to hope that the Agent follows directions from the execution prompt to take these steps).

Changes in this MR:

1. Moving git logic from the execution prompt, into multiple DeterministicStepComponent in fix_pipeline.yml
2. Removed some context gathering tools from the execution agent, since it should get context from the context component
3. Added context:project_http_url_to_repo to the state in /experimental/flows/base.py
4. Some cleanup of prompt wording and layout.

Graph structure before:

Graph structure after:

How to set up and validate locally

Follow the validation steps in this MR

Merge request checklist

• Tests added for new functionality. If not, please raise an issue to follow up.
• Documentation added/updated, if needed.

Closes #1409 (closed)