Remove I/O Extended stuff

I've done the following:

 1. Removed all I/O extended-related strings (and some live/non live, plus unused ones, as well)
 2. Removed all references to unused "I'm attending" preference, code, and resources
 3. Removed all livestream and references from the ContentProvider, and the backing database
 4. Bumped data version to 27 and database version to 106 (v1.2)
 5. Provided and tested DB update path from version 105 to version 106 (not as in-depth as I should've, but it's my first time providing DB updates that aren't simple drop-and-recreate ops)
 6. Removed YouTube permission and some code (not fully, have to wait for confirmation from Al whether we will eventually have sessions videos uploaded to YouTube, and if we want them in the app)