feat(lsp): goto declaration for trait methods

[kobyhallx]

Considering snippet below

trait Fieldable {
    fn to_field(self) -> Field;
}

impl Fieldable for u32 {
    fn to_field(self) -> Field {
        let res = self as Field;
        res * 3    
    }
}

fn main(x: u32) {
    assert(x.to_field() == 15);
}

User should be able to navigate to declaration of to_field when on that symbol of line assert(x.to_field() == 15); which should result in navigation to fn to_field(self) -> Field; symbol of trait Fieldable.