Enable interactions to work offline

[vojtechjelinek]

Some of the interactions don't work on flaky connections, they fail to load or produce errors when the connection is disabled in an exploration player.

InteractiveMap — needs a connection to load parts of the map
MusicNotesInput — needs a connection to load the images of the notes, should be quite easy to fix
PencilCodeEditor — needs a connection to fully load the editor

Investigate these and try to fix them.

[Red-0111]

Hi, I can take up this issue.

[seanlip]

@Red-0111 Per the guidance at https://github.com/oppia/oppia/wiki/Contributing-code-to-Oppia#choosing-a-good-first-issue, please provide an explanation of what your PR will do (with names of files you're changing, what you plan to change in each file, etc.). If it looks good, we can assign you to this issue.

Please also follow the other instructions on that wiki page if you have not yet done so. Thanks!

Also I recommend focusing on starter issues and issues that are marked high-priority/priority in the first 3 project boards here: https://github.com/oppia/oppia/projects?query=is%3Aopen. You will get more support that way. Thanks.