Re-initialize the RAWG API when saving settings

[breakid]

Problem: The rawgAPI was only set when the plugin initially loaded. A user could enter their API key on the settings page, but the plugin wouldn't start using the API key until the plugin was reloaded (e.g., when the user closed and re-opened Obsidian). I believe this to be the most likely cause of the 401 errors that would seemingly resolve in time.

Solution: Added a line to the saveSettings() function that re-initializes the API, thus immediately picking up on changes to the API key.

Testing:

• Original
  1. Successfully searched for a game with a working API key (to ensure everything was working to begin with)
  2. Changed the API key to something obviously invalid (e.g., 5555555)
  3. Searched for a different game
     • The search still worked because the API wasn't re-initialized and was still using the valid key
• Modified Version
  1. Successfully searched for a game with a working API key (to ensure everything was working to begin with)
  2. Changed the API key to something obviously invalid (e.g., 5555555)
  3. Searched for a different game
     • The search failed with a 401 error because the API key was invalid
  4. Refreshed my RAWR API key
  5. Configured Game Search to use the new API key
  6. Searched for a game
     • The search completed successfully (less than a minute after refreshing the key)

[CMorooney]

hah! good catch, I feel a little silly for missing it all this time

the PR, explanation, and README update is much appreciated!