COLLATE keyword

The `COLLATE` keyword is supported by Mysql and MariaDB and other SGBDs.

Example:
```sql
SET NAMES 'utf8' COLLATE 'utf8_general_ci';
```
CLI output :
```
./vendor/bin/lint-query --query "SET NAMES 'utf8' COLLATE 'utf8_general_ci';"
#1: Mot clé non reconnu. (near "COLLATE" at position 17)
#2: Jeton inattendu. (near "'utf8_general_ci'" at position 25)
```