Merge #9039

9039: feat: Complete fields and methods with `self.` prefixed when inside methods r=matklad a=Veykril


![w65NbjkZiG](https://user-images.githubusercontent.com/3757771/119984385-a0111700-bfc1-11eb-9dbf-52fdaa4d72b5.gif)
Closes #7173

Co-authored-by: Lukas Wirth <lukastw97@gmail.com>

crates/rust-analyzer/src/to_proto.rs

@@ -1178,6 +1178,7 @@ mod tests {
                 &ide::CompletionConfig {
                     enable_postfix_completions: true,
                     enable_imports_on_the_fly: true,
+                    enable_self_on_the_fly: true,
                     add_call_parenthesis: true,
                     add_call_argument_snippets: true,
                     snippet_cap: SnippetCap::new(true),