Address resolvers

[NotNite]

Heya, first time contributing to a C++ project so let me know if I fucked something up. This PR adds a Lua API to resolve strings in the Address field:

regenny:add_address_resolver(function(str)
  if str == "test" then
    return 0x188279445F0 -- Hardcoded example for now
  end
end)

This is the one big feature I'm missing to be able to switch from ReClass.NET (we have a plugin that does similar in the FFXIV community). The idea I have is to plug our class data into ReGenny to then have it automatically resolve a singleton name to its instance in memory.

In order to build ReGenny I had to update vcpkg, as package URLs no longer existed. I had to change a few includes but everything seems well. I hope this isn't an issue!

[praydog]

Not seeing any issues with the code at first glance, I'll wait for @cursey's thoughts on this.

[NotNite]

Thanks! I'm currently using it over in https://github.com/NotNite/csgenny and it seems to work OK. Will comment if I find any issues.

[cursey]

LGTM