lsp: implement modules support

[gerau]

As modules has been added into compiler, we should also introduce it support in LSP. Adding support requires introducing some features in LSP, because paths resolution of modules is happening outside of compiler.

Here is an approximate list of features which needed to be implemented:

• Path resolution of modules, as it is done in [simplex](https://github.com/BlockstreamResearch/smplx) via Simplex.toml or/and automatic path resolution based on document location;
• Refactoring of how documents is created and handled inside LSP -- it was originally made with support of multiple files in mind, but it's vision is differs from what is happening right now;
• Support of "go to definition" and similar functionalities of LSP across the project.