Fix `Clone` for Merkle Tree Path

[tsunrise]

Description

The derive of Clone trait for Path<P> doesn't work well, because it implicitly adds a trait bound P: Copy. In most cases, when cloneing a path, user might encounter the following compile error:

the following trait bounds were not satisfied:
            `P: Clone`
            which is required by `ark_crypto_primitives::Path<P>: Clone`

This PR removes the derive and implements Clone trait manually using Derivative instead. Also added Clone for constraint path.

---

Before we can merge this PR, please make sure that all the following items have been checked off. If any of the checklist items are not applicable, please leave them but write a little note why.

• [x] Targeted PR against correct branch (main)
• [x] Linked to Github issue with discussion and accepted design OR have an explanation in the PR that describes this work.
• [x] Wrote unit tests
• [x] Updated relevant documentation in the code
• [x] Added a relevant changelog entry to the Pending section in CHANGELOG.md
• [x] Re-reviewed Files changed in the Github PR explorer

[weikengchen]

I used derivative instead. Does that work for the application (I assume LDT)?

[tsunrise]

I used derivative instead. Does that work for the application (I assume LDT)?

Yes it works! Wow derivative is great. I'm going to learn how to use it

[weikengchen]

Derivative indeed is no magic. Just a macro that writes the code that we manually implemented Clone with.

[tsunrise]

Derivative indeed is no magic. Just a macro that writes the code that we manually implemented Clone with.

haha quite handy. The change looks good to me. Feel free to merge