Refactor/divide common.rs into smaller files

[fadeevab]

Reasons / Why

1. common.rs is ~2600 lines long, it's pretty huge.
2. It takes roughly 3 thousand light years 10+ seconds for rust-analyzer to recompile it at every change (Ctrl+S)... on my average laptop.
3. Another reason for refactoring is the fact that common name is too... common.

I was trying to make a simple patch into common.rs, and clippy recompilation delays made it quite challenging.

Thanks :)

[frol]

@fadeevab common.rs is a pile of ugly hacks that we have to decouple into dedicated crates. We have started to work on it here: https://github.com/akorchyn/near-api