svm: only inspect loaded accounts

[2501babe]

Problem

as-written, inspect_account is called on every LoadedTransactionAccount produced by load_transaction_account, but some of these are pseudo-accounts. namely:

• instructions sysvar: transient blob data produced for a specific transaction
• account overrides: mocked-out account states used for transaction simulation
• program cache entries: these are real accounts, but necessarily read-only, so they dont need to be inspected. but the AccountSharedData produced from the cache has an empty data vector and may erroneously be marked as executable, so it should not be pushed back to the bank

Summary of Changes

only call inspect_account on accounts that are retrieved from accounts-db, or accounts to be newly created

[2501babe]

put back into draft until tests pass, my initial version of this i forgot accounts are inspected in validate_transaction_fee_payer too. im 70% sure account overrides is only for things that should never be seen by accounts-db, but i dont know the code where its used upstream from svm, so if there was a reason you were inspecting these please correct me. im 100% sure that program cache entries and instructions sysvar should never be inspected

[brooksprumo]

Code looks good to me.

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im 70% sure account overrides is only for things that should never be seen by accounts-db, but i dont know the code where its used upstream from svm, so if there was a reason you were inspecting these please correct me.

I'm not familiar with account overrides, so I defer to your expertise here 😸

im 100% sure that program cache entries and instructions sysvar should never be inspected

👍

[brooksprumo]