Merge #3696 #3698 #3703

Merge #3696 #3698 #3703

3696: vscode: more type safety r=matklad a=Veetaha

3698: Consider references when applying postfix completions r=matklad a=SomeoneToIgnore

Sometimes my RA debugging workflow breaks because `.dbg` is applied to the variable that is used later in the code.
It's safer to consider the refences to avoid this for completions that may trigger the move.

3703: Don't try to enable proposed API's on stable r=matklad a=matklad

bors r+
🤖

Co-authored-by: veetaha <veetaha2@gmail.com>
Co-authored-by: Kirill Bulatov <mail4score@gmail.com>
Co-authored-by: Aleksey Kladov <aleksey.kladov@gmail.com>