Can't rename TS 3.8 private fields

[gregvanl]

• VSCode Version: 1.42 Insiders
• OS Version: Windows 10

Found will testing #89387

Steps to Reproduce:

1. Create a private field (#name: string).
2. Try to rename (F2) the symbol.

Get a message "You cannot rename this element".

You can rename 'name' -> '#name' but can't rename after changed to '#name'.

[mjbvz]

Opened microsoft/TypeScript#36481 to track upstream