Raw string literals have very poor support

### Environment Data
VS Code version: 1.99.3
C# Extension version: 2.74.24

### Steps to Reproduce

1. Attempt to declare a raw string literal anywhere by typing its opening 3 (or more) quotation marks:
```cs
string s = """|
```
Where `|` is the cursor position.

### Expected Behavior

The corresponding 3 quotation marks should be inserted on the other side of the cursor.
Inserting a new line then formats the quotation marks like below:
```cs
string s = """
|
"""
```
Where `|` is the cursor position.

### Actual Behavior

The corresponding 3 quotation marks are not inserted.
Inserting a new line results in the cursor being on the same level as the declaration:
```cs
string s = """
|
```
Where `|` is the cursor position.