feat: Add "Discard Changes" button on Edit Wheel screen

[phoebe-buffay]

What feature?

When user is on Edit Wheel screen, and makes some changes in estimation, then decides that it's not needed to be changed and wants to return to the previous estimation statement, then they can click on Discard Changes button to reset just made changes

There is Field Estimation component, which has Save Changes button

1. Add "Discard Changes" button under Save Changes button
2. Discard Changes button should be secondary (white inside) and should have the same properties as Save button
3. Discard Changes button should be inactive until user makes any changes in estimation
4. If user makes some changes in estimation and then clicks on Discard Changes, then the estimation statement should return 5. to last saved statement
5. If user clicks on Discard Changes button, they should remain on the Edit Wheel screen
6. After clicking and discarding, button should become inactive again until new changes are done

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