[FORMATTING] BigQuery: Doesn't handle escaped quotes in raw strings

**Input data**
Reproduces on https://sql-formatter-org.github.io/sql-formatter/

Which SQL and options did you provide as input?
Language: BigQuery

```sql
SELECT
    regexp_extract(event_properties, r'Email": \'(.*?@.*?)\'')
FROM test
```

**Actual Output**

```
Parse error: Unexpected "@.*?)\'') " at line 2 column 50. SQL dialect used: "bigquery".
```
