change(consensus): Allow configurable Nu5 activation height on Regtest

[arya2]

Motivation

We want to allow configuring an NU5 activation height on Regtest. This was removed in a recent PR because I thought Zebra didn't support Canopy block construction, it does, it was the proposal_block_from_template() function used in tests and the internal-miner that only worked with NU5.

PR Author Checklist

Check before marking the PR as ready for review:

• [x] Will the PR name make sense to users?
• [x] Does the PR have a priority label?
• [x] Have you added or updated tests?
• [x] Is the documentation up to date?

For significant changes:

• [x] Is there a summary in the CHANGELOG?
• [x] Can these changes be split into multiple PRs?

If a checkbox isn't relevant to the PR, mark it as done.

Solution

• Accept a current_network_upgrade argument in proposal_block_from_template()
• Select which field from the template should be used in the block based on the current network upgrade
• Use the testnet_parameters.activation_heights.nu5 field as the NU5 activation height on Regtest

Related Changes:

• Updates with_activation_heights() to overwrite activation heights for all network upgrades except Genesis

Testing

The regtest_submit_blocks() test was updated to submit Canopy blocks and switch to NU5 blocks at height 100

Review

Anyone can review.

Reviewer Checklist

Check before approving the PR:

• [ ] Does the PR scope match the ticket?
• [ ] Are there enough tests to make sure it works? Do the tests cover the PR motivation?
• [ ] Are all the PR blockers dealt with? PR blockers can be dealt with in new tickets or PRs.

And check the PR Author checklist is complete.