Using `require` to inject file contents into JS files causes issues with unit tests

We cannot write unit tests for some files if using code as follows:

const addRunCellHook = require('../../pythonFiles/vscode_datascience_helpers/kernel/addRunCellHook.py');

• We might want to consider removing such webpack specific code from our code and use some other way to inject the file contents.
• Or we need way another way to write unit tests for such files.
• Or we could have a simple provider that provides the contents of these files.
• We end up duplicating the files (its in the source code as well as vsix)

[rchiodo]

Hmm, I think the file system could read it from the extension URI. I don’t think these need to be embedded.

[rchiodo]

@sadasant’s other fix in this area should be applicable.