refactor: code

[alexander-akait]

Here:

• simplify logic
• avoid overhead Promise.resolve() (not eveywhere, we need improve it more)
• reduce complexy
• types fixes
• TODO for the next major release
• avoid extra clonning and other unnecessary overhead
• and more

It is the first part of refactor, we need:

• avoid using Promise.resolve()/etc in favor async/await
• remove CacheChildCompiler in favor built-in webpack cache (compat with current behaviour, at the end this option will do nothing and just will be removed)
• autogeneration types from jsdocs
• readable code and simple code