Add stdlib-path as cli argument

[ygorpontelo]

This is something i don't expect to change much per project, so would be nice to able to pass that to the server when the extension starts. If i want to use this feature i need to create the json config in my projects, which is annoying as it's always the same path.

One other option would be for the server to search for the c3lsp.json in a default location, like the directory where the bin is, and use that one as the default if it exists. If there is a json in the project directory, then it overrides that default one.

On a side note, thanks for creating the lsp! It helps a lot :D

[pherrymason]

Implemented new stdlib-path argument.
This should be updated in lsp clients to support it (for example vscode extension).

About the general c3lsp.json, it's a good idea. Will leave this issue open to keep track of that.