Do not show cardsets from non-friends set to friends only

[JasonWu00]

This PR modifies the search query in server/routes/cardsets.js, in conjunction with adding a new column to the Cardsets table.

Full list of changes:

• Updated .gitignore to ignore googleapis.json
• Added the isFriendsOnly column to the MySQL database using MySQL Workbench
• Modified the server/routes/cardsets.js search query with new rules; the search will return cardsets that:
  • have their isFriendsOnly value set to false
  • have their isFriendsOnly value set to true, AND belongs to a friend of the user
  • This required a subquery to extract the IDs of all of the user's friends.
• Required the Friend table in cardsets.js to facilitate the above change

This PR only affects the back-end implementation. The front-end addition of an option for users to set a cardset as friends only is not included.

[render[bot]]

Your Render PR Server URL is https://audiocard-server-pr-161.onrender.com.

Follow its progress at https://dashboard.render.com/web/srv-co8q62v79t8c73dvn3c0.

[JasonWu00]

Hold off on the reviews for a moment, there seems to be a failed check that I need to fix first.

[render[bot]]

Your Render PR Server URL is https://audiocard-client-pr-161.onrender.com.

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