Al: Use new vscode.DocumentSymbol instead of vscode.SymbolInformation for document symbols returned from the language server

[anzwdev]

Could you use new DocumentSymbol type instead of SymbolInformatin for list of document symbols returned from al language server? They support tree structure of symbols which then can be used by both vs code outline view and breadcrumbs. New type allows also to return more detailed symbol information in "details" property. It could be used to return nice function signatures with information if function is public or private.

[StanislawStempin]

We have recently improved the SymbolInformation to be working correctly with the hierarchical Outline view. We will look into DocumentSymbol as well, thanks for the suggestion.