"Undo" functionality in flash messages (issue #64)

[wuletawwonte]

Description

This PR addresses issue #64. I have implemented an undo action that allows users to revert their last action via a button in the flash message as per the design in Figma.

How it works:

1. Each time an action (create, destroy) is performed, it is stored in the session (session[:last_action])
2. The flash message partial conditionally displays an "Undo" button based on if the undo path is available that allows the user to revert the action
3. The undo action then retrieves the last action from the session and reverts it.

How has this been tested?

Please mark the tests that you ran to verify your changes. If difficult to test, consider providing instructions so reviewers can test.

• Manual testing
• System tests
• Unit tests
• None

Checklist

• CI pipeline is passing
• My code follows the conventions of this project
• I have performed a self-review of my code
• I have commented on my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (if applicable)
• I have added seed data to the database (if applicable)

Release tasks

Add any tasks that need to be done before/after the release of this feature.

Screenshots/Loom

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