[analyzer] Add benchmark for many 'prefer_single_quotes' violations

For the select all one I get
50: 0.310976 seconds
100: 1.054733 seconds
200: 5.535353 seconds
400: 36.099675 seconds
800: 247.919461 seconds

Disabling that (so I can go higher) for the
"Subsequent action call 1" (simulating moving the cursor down a line
in the IDE in the file) I get
100: 0.047451 seconds
200: 0.079821 seconds
400: 0.160073 seconds
800: 0.451288 seconds
1600: 1.311321 seconds
3200: 5.549266 seconds
6400: 32.955526 seconds

Note that for all of this it's just a single file with <size> lines
looking like

```
"num": "num",
```

so even though 6400 is a "large number" it's not entirely unrealistic.

Change-Id: I5c2a51822c0748b4a71d98cef9caeb3e30aec5bc
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/425503
Commit-Queue: Jens Johansen <jensj@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>