Add support for snapshot/rollback in local machines

[edubart]

This is an experimental PR adding support for performing snapshot/rollback on local machines. Making the APIs available in Windows and WASM. It uses the naive implementation of duplicating the whole machine memory.

This PR does not try to optimize this operation to compete with JSONRPC fork(), it just provides the naive implementation that will work on any system.

TODO

• add lua tests
• make deep copy of merkle tree and use it
• avoid deep copy of read only PMAs and design a way to share them between multiple machines
  • introduce read only flash drives, so we can avoid copying them, useful for machines with read-only rootfs
• optimize Windows memory map to not use calloc
• add disable CMIO option again, so we don't have to deep copy them on WASM
• add fork method to machine C API?

Benchmark

To comparise the of performance of local vs jsonrpc machines, I tested booting the last release of tools rootfs tanking random roollbacks:

math.randomseed(0)
while not machine:read_iflags_H() do
    machine:snapshot()
    machine:run(machine:read_mcycle() + 1000)
    if math.random() < 0.3 then
        machine:rollback()
    else
        machine:commit()
    end
end

This is the result:

local       67 iterations/s
jsonrpc    895 iterations/s

Therefore jsonrpc is about 13x times faster than local, the performance for local would be even worse from bigger machines.

[edubart]

This PR is being superseded by #281 , which will be superior and faster.