LSP symbol tables

[onbjerg]

Describe the feature

We should walk the HIR to generate a symbol table which is useful for things like go to definition, workspace and file symbols, go to declaration and find usages.

The symbol table should be divvied up into different scopes, as querying by scope is useful for features like autocomplete. Additionally, it should be possible to map an offset in a file to a scope and a symbol, to find the symbol under the current cursor.

Additional context

No response