Feature request: Add a way to run lua commands before lua scripts in defineCommand/eval run?

[TysonAndre]

E.g. this would allow mocking the subset of functionality that was used in an application for #1143 or the currently missing cjson or other applications that aren't supported

This would involve something similar to defineRedisObject in src/commands/defineCommand.js

• where luaInit would get called after defineRedisObject is called but before the lua user code runs.

const redis = new RedisMock({
    luaInit: (vm) => {
        // vm.defineGlobalFunction/luaExecString/lua_setglobal calls
    }
});