added eslint-plugin-import with config

[coado]

Summary

The PR introduces a eslint-plugin-import mainly for maintaining a consistent order of imports. It is the most used eslint plugin for such cases and has the greatest number of available configs. This starting configuration consists of a rule that will keep imports in this order: builtin -> external (with imports from react-native at the top) -> internal -> parent -> sibling -> index. Besides that, I've added rules that will prevent self imports, cycles, and useless path segments. Also, I think that it's nice to keep all imports at the top of the file and an empty line after them.

Let me know what do you think about this configuration!