When `show_tx_calls` is manually set to true, show all the calls from the EVM
to the host, including name, arguments and results.
For example this shows each call to `setStorage`, the key, value and storage
result. This output allows the externally-visible activity of an EVM to be
seen, and it's been useful for guessing what went wrong when a test fails.
In theory, if two EVMs show the same activity in this log, they should have the
same effect on account states, gas, etc. and the same final `roothash`
(which is the only value some tests check).
ps. Ideally we'd use `{.push show.}`...`{.pop.}`, just like with `inline`.
But we can't: https://github.com/nim-lang/Nim/issues/12867
Signed-off-by: Jamie Lokier <jamie@shareable.org>
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