EVM: extend tracing API

[canepat]

Currently, support for tracing in evmone is guaranteed by the Tracer interface, which happens to be good for many use cases, but not all of them: in particular, it lacks some key information for implementing debug and trace JSON-RPC API tracers (e.g. dynamic gas cost for opcodes, see #2153 #2167 #2172 #2181 #2187 #2211) and execution call tracer (e.g. some early-return positive cases and some negative scenarios, see #1706 #1710 and #1871).

Our idea is, first of all, extending the current tracing API in evmone, for the purpose of exporting all the needed information and covering all the existing use cases. Then, we will do some performance assessment and evaluate alternative designs to improve the numbers.

@chfast we will do the first part of this work on our fork of evmone and will ask for your review when done, then for your advice on the second part.

• tracing API extension and changes in debug tracers rpcdaemon: gas cost from EVMONE for debug family API #2325
• changes for tracing API extension in trace tracers
• performance evaluation and alternative designs