Adjacent string literals of the same type should be on separate lines

Suppose I have:

```python
print("Line 1\n"
"Line 2\n"
"Line 3\n")
```

yapf (0.31.0) wants to format it as:

```python
print("Line 1\n" "Line 2\n" "Line 3\n")
```

I argue that this is clearly against the author's intention, and having adjacent string literals of the same type (i.e., both are unadorned double-quoted strings, both are unadorned single-quoted strings, both are raw strings, both are f-strings...) makes no sense since they could have been combined into a single string literal in that case.

If that reasoning isn't compelling enough, then alternatively check if a string literal ends with a `\n`, and never put an adjacent string literal to the right of it.