Upgrade to NU5 testnet 2 versions of librustzcash, zcash_script, orchard, halo2_proofs

[teor2345]

Motivation

Currently, Zebra and zcash_script depend on a git version of the following shared Zcash crates:

• zcash_history
• zcash_primitives
• zcash_note_encryption
• orchard
• incrementalmerkletree
• equihash
• zcash_script

And we depend on pre-NU5 versions of:

• halo2

We need to update to the NU5 testnet 2 versions of these crates.

Tasks

1. Wait until the zcashd team releases 4.7.0, with the NU5 testnet 2 versions of librustzcash and orchard

halo2_proofs

Try:

halo2 = { package = "halo2_proofs", version = "=0.1.0-beta.2" }

"and then you only need to focus on the API changes, not renaming the imports everywhere."

See also the changelog for `halo2_proofs 0.1.0-beta.2 for all of the API changes relevant to this upgrade.

(This was a separate ticket before, for reference: #3600)

librustzcash

If zcash/librustzcash#459 got merged:
2. In the next steps, update zcash_script and Zebra to the latest git commit of zcash/librustzcash/master

If zcash/librustzcash#459 is still open:
2. Merge zcash/librustzcash/master into ZcashFoundation/librustzcash/download-sprout-params
3. Tag ZcashFoundation/librustzcash/download-sprout-params as a beta release, so zcash_script and Zebra can depend on it

zcash_script

4. Upgrade zcash_script to the NU5 testnet 2 orchard and librustzcash, removing the git versions in Cargo.toml
5. Revert module structure changes if needed: Revert zcashd Orchard module structure changes zcash_script#27
6. Remove the git patches in zcash_script/Cargo.toml
7. Merge the upgrade and module structure PRs to zcash_script/master
8. Tag a zcash_script beta release

Zebra

9. Upgrade Zebra to the NU5 testnet 2 orchard and librustzcash, removing the git versions in Cargo.toml
10. Upgrade Zebra to the latest version ofzcash_script (git tag)
11. Remove the exceptions for orchard, librustzcash, and dependencies in deny.toml
12. Merge the Zebra upgrade PR along with the PR for ticket Rollback NU5 testnet 1, and set consensus parameters for testnet 2 #3018

[mpguerra]

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