Enables lazy loading by default in all tests by changing the conversion from Account to PartialAccount to only represent the minimal account and by setting TransactionContextBuilder::is_lazy_loading_enabled = true. Builds on top of #1955.

The changes:

• Remove TransactionArgs::foreign_account_inputs. So, foreign accounts are now no longer loaded upfront but only when they are needed.
• Change how Account is converted to PartialAccount . Essentially: New accounts are converted to a "full" partial representation and existing accounts are converted to a minimal representation.
  • This cleaned up a few lazy loading things in test code like minimal_partial_account.
• MockChain::get_foreign_account_inputs returns Account instead of PartialAccount. See Remove foreign_account_inputs field from the TransactionArgs #1473 (comment) for details.
• transaction_with_stale_foreign_account_inputs_fails was removed because the checks it was testing no longer exist. In principle, we could move this check to TransactionExecutorHost::on_foreign_account_requested but in practice it makes little difference: We're already in the middle of transaction execution and so whether the host aborts or the kernel isn't very important. The pro for having it is that the host could return a better error than the tx kernel while the pro for not having it is that it makes testing the kernel logic possible at all. For now it's the latter.
• Overhaul test_epilogue_asset_preservation_violation_too_few_input and test_epilogue_asset_preservation_violation_too_many_fungible_input to be more concise, execute a full transaction instead of execute_code. This turned out to be unnecessary in hindsight, but also partially addresses Consider removing create_mock_notes #1845, which I think is a plus.

closes #1473