Enable lazy loading for tests using `TransactionContext::execute_code`

[PhilippGackstatter]

We currently have lazy loading enabled only for a handful of tests. One primary blocker is that we cannot easily enable lazy loading when executing arbitrary code with TransactionContext::execute_code, because MockHost does not support it. As it is now, we would have to integrate lazy loading into MockHost which seems like an unnecessary maintenance burden. Ideally, we can use the TransactionExecutorHost instead and remove MockHost entirely.

In execute_code this could look something like this:

let account_procedure_index_map = AccountProcedureIndexMap::new(
    [self.tx_inputs().account().code().commitment()],
    advice_inputs.as_advice_inputs(),
)
.expect("TODO");

let host = TransactionExecutorHost::<'_, '_, _, UnreachableAuth>::new(
    self.tx_inputs.account(),
    self.input_notes().clone(),
    self,
    ScriptMastForestStore::default(),
    account_procedure_index_map,
    None,
    self.tx_inputs().block_header().block_num(),
    self.source_manager.clone(),
);

The above works, but trying to pass it to CodeExecutor doesn't because it requires a SyncHost but TransactionExecutorHost implements AsyncHost. We could instead make CodeExecutor use the FastProcessor, but it does not currently let us access the process state after execute, like Process does. This is already implemented done through 0xMiden/miden-vm#2052, and so we should be able to do this after we have upgraded to the next VM.

At that point, we should ideally be able to enable lazy loading throughout the codebase, and independent of whether TransactionContext::execute or execute_code is used. This means removing TransactionContextBuilder::enable_partial_loading and everything that depends on it.

Once we have this, we can also remove the foreign_account_inputs parameter from TransactionArgs::new, i.e. close #1473. Until then, we still need it to load foreign account code for execute_code tests (a couple of tests in test_fpi.rs).

This is a follow-up to #401.

[PhilippGackstatter]

This issue basically prevents testing of storage map and asset lazy loading for foreign accounts. To test that, I'd like to enable lazy loading everywhere by changing the conversion from AssetVault to PartialVault and StorageMap to PartialStorageMap to only track the minimal necessary data. That causes lazy loading of all vault and storage map accesses. Because the MockHost currently doesn't do lazy loading, this causes failures in many tests that use execute_code. Since the VM release is around the corner, it doesn't seem worth modifying the MockHost, but I'm also hesitant to implement the above feature without testing it at all.

So just to document it, as part of this issue we should also make sure that the above feature is tested in case it isn't already by the time it lands.