fix(rpc): Return full network upgrade activation list in getblockchaininfo method

[arya2]

Motivation

Lightwalletd relies on the Sapling activation height from the getblockchaininfo response to skip syncing pre-Sapling blocks.

Solution

• Adds a full_activation_list() method on Network
• Replaces the call to activation_list() in the get_block_chain_info RPC method with a call to full_activation_list()
• Updates docs

Tests

Adds a vector test to check that full_activation_list() returns all implicit network upgrade activations

PR Author's Checklist

• The PR name will make sense to users.
• The PR provides a CHANGELOG summary.
• The solution is tested.
• The documentation is up to date.
• The PR has a priority label.

PR Reviewer's Checklist

• The PR Author's checklist is complete.
• The PR resolves the issue.

[oxarbitrage]

I think the changes looks good but can we add more context? Do we have a lightwalletd issue or discussion we can link here ?

[mpguerra]

Related to: https://discord.com/channels/809218587167293450/809251029673312267/1263134871505735680

[daira]

utACK

[oxarbitrage]

Related to: https://discord.com/channels/809218587167293450/809251029673312267/1263134871505735680

Thanks, according to the discord discussion it seems the PR fixes the issue.