feat(vm): Allow caching signature verification

[slowli]

What ❔

Allows caching signature verification (more precisely, ecrecover output for L2 transactions using the default AA) in the fast VM.

Why ❔

Signature verification takes ~50% of the execution time for "simple" transactions (e.g., base token and ERC-20 token transfers), so caching it may improve performance.

Checklist

• PR title corresponds to the body of PR (we generate changelog entries from PRs).
• Tests for the changes have been added / updated.
• Documentation comments have been added / updated.
• Code has been formatted via zkstack dev fmt and zkstack dev lint.

[slowli]

The PR doesn't include the ability to disable signature verification in the state keeper (and maybe other places, e.g., in subsequent gas estimation / tx submission VM runs). I'd prefer for it to be implemented in a separate PR.

Locally (on an M2 Max Macbook), disabling signature verification improves performance ~2x on simple transactions, like base / ERC-20 token transfers:

fill_bootloader/transfer/1000
    time:   [274.78 ms 277.20 ms 281.97 ms]
    thrpt:  [3.5465 Kelem/s 3.6075 Kelem/s 3.6393 Kelem/s]
fill_bootloader/no_sigs/transfer/1000
    time:   [138.68 ms 139.63 ms 140.68 ms]
    thrpt:  [7.1085 Kelem/s 7.1615 Kelem/s 7.2109 Kelem/s]

Curiously, this doesn't translate to the instruction-counting bench; there, disabling signature verification only leads to ~10% instruction count / estimated cycle count improvement.

A potential alternative would be to switch the default AA for "signature-less" execution with one that skips signature verification. The downside is having to keep multiple default AA implementation, and it could have unobvious pitfalls (e.g., IIUC, the default AA bytecode hash must be the same regardless of the implementation, so for the signature-less one, it won't correspond to the actual bytecode).