Function get_diagnostics_as_string 

pub fn get_diagnostics_as_string(
    db: &dyn Database,
    crates_to_check: Option<Vec<CrateId<'_>>>,
) -> String

Returns a string with all the diagnostics in the db.

This is a shortcut for DiagnosticsReporter::write_to_string(&mut string).check(db).

If crates_to_check is Some, only diagnostics for these crates will be checked. If crates_to_check is None, diagnostics for all crates in the db will be checked.