Add custom silence skip sounds

[gdavis]

The player is built to handle different silence skip sounds. Add new custom sounds that would be unlocked as part of the pro or premium purchases.

Sound ideas:

• Blade sharpen (cut through silence)
• Better snip or blade slice
• Light bells (like a spell cast)
• Animal grunt or something?
• Burp

Implementation Steps:

• [x] Update audio player set and update the selected sound
• [x] Add UI for selecting the settings
  • [x] macOS Preference Drop Down
  • [x] iOS Table Selection
• [x] Add credit for using sounds from: https://gfxsounds.com/