Fix broken original zcash tests

[dimxy]

There are several zebra original tests broken due to some changes we made for komodo network:

• MAX_MONEY changed
• interest calculation added
• address prefix changed
• min difficulty changed
• target spacing for testnet changed
• zcash network upgrades activation heights changed. in total around 20 tests are broken when cargo test is executed. We need to fix those tests.

[dimxy]

For discussion: I am thinking if it is possible to ensure that the original zcash tests work without our fixes, so we could always pull their latest changes with tests working. As stated above zcash tests are broken due to network parameters changed for the kmd network. So I think maybe we could leave their network parameters intact and create new networks for kmd main and testnet with our specific parameters so we always will add komodo rules only for our networks. This would make the original zcash rules working for their network parameters and zcash tests should work as well. (Ofc there some difficulties with that, f.e. having different MAX_MONEY for both networks - this would require changes in core level like add the network param to the Amount object or provide access from Amount to the current network in another way)

[dimxy]

some tests were fixed for komodo the rest were disabled (PR #2)