[5.8] Unquote JSON values on MySQL

[staudenmeir]

Among the four supported databases, only the MySQL implementation returns quoted JSON values:

DB::table('users')->value('options->language');

// MySQL/MariaDB:   "en"
// Other databases: en

#24817 added the ->> operator that returns unquoted values. But this doesn't change the default behavior and is incompatible with the other databases (#25726): If your application expects unquoted values on MySQL and PostgreSQL, you have to detect the database and then use 'options->>language' or 'options->language'.

I think the MySQL implementation should be consistent with the other databases and return unquoted values by default. I would argue that an unquoted value is the result a user expects.

As a breaking change, this targets 5.8.

[X-Coder264]

@staudenmeir Could you please document this breaking change in the upgrade docs for 5.8?