Maximum file size limit per package blocks content writers

[shakao]

Describe the bug We have a size limit of 64k per file when loading an extension or tutorial. This is quite low; @riknoll ran into it when putting a few background images into a sprite pack and a forum user hit the limit with a 9-step tutorial that had a tilemap in each step (https://github.com/SCjoh/kodekraft-tutorial-1/blob/master/README.md).

We also don't report this error in any way that a user could act on--this person was using the tutorial tool to develop and preview their content, and everything worked correctly there. When loading into the editor, we give a pretty unhelpful "check that the tutorial is valid" message.

Reported here: https://forum.makecode.com/t/tutorial-links-stop-working/3115

Expected behavior I think we should up the size limit (or we could have a larger size for md and jres files?) and also reflect this size limit in the tutorial tool. Error messaging in the editor could also definitely be improved.

[riknoll]

It's even worse for an extension: no error message it just doesn't show up in the search results. Had to check the console to figure out what was going on.