save ScriptExecutionMetrics during CScriptCheck
CScriptCheck represents a full closure of the call to VerifyScript.
Currently it just saves the outputted error code; update it to also save
the metrics return value.
A small test (taking advantage of an existing test that uses CScriptCheck) is
Depends on D4918
Test Plan: ninja all check
Reviewers: #bitcoin_abc, deadalnix
Reviewed By: #bitcoin_abc, deadalnix
Differential Revision: https://reviews.bitcoinabc.org/D4920