add(test): Add serialized NU5 blocks to test vectors

[upbqdn]

Motivation

Close #2409, #9090 and #9088.

Solution

• Add suitable serialized Mainnet & Testnet NU5 blocks and their anchors to test vectors.
• Remove wrong Testnet NU5 blocks.
• Add has_transparent_inputs to Transaction

Tests

• Remove unneeded test for fake V5 txs.
• Use real V5 txs where appropriate. This uncovered some malfunctioning tests, for example 34e985b.
• Fix failing tests. This turned out to be much more work than I expected.
• Use Network::iter instead of only Mainnet txs.

Follow-up Work

• The tx verifier does not enforce using the correct consensus branch ID in the SIGHASH computation #9089

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.