feat(script): add current_memory syscall

[mohanson]

What problem does this PR solve?

Problem Summary:

There is no way to get peak memory in the script.

What is changed and how it works?

What's Changed:

Add a new syscall current_memory which returns the peak memory.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code ci-runs-only: [ quick_checks,linters ]

Release note

Note: Add a note under the PR title in the release note.

[eval-exec]

The CI job for cargo-deny has failed, but it has been resolved in the develop branch.

[mohanson]

The CI job for cargo-deny has failed, but it has been resolved in the develop branch.

CI failed on macOS now. Some unittest cases panics.

[eval-exec]

test_collision_and_send_missing_indexes failed. I'm investigating this...

I'm trying to reproduce this in my host (Linux):

while true;
  do cargo test -p ckb-sync -p ckb-chain \
  relayer::tests::block_transactions_process::test_collision_and_send_missing_indexes \
  -- --nocapture;
done

@chenyukang and I can't reproduce this. Try to rerun the failed CI job...