standardize on using yarn and yarn lockfile

[shiftkey]

The other projects in this organization use yarn, and this is currently the only exception:

• [ ] import a vendored yarn and add the related .yarnrc config
• [ ] regenerate the lockfile
• [ ] remove any package.json scripts that might use npm directly
• [ ] test a release using yarn and update documentation

[j-f1]

What do you think about making a desktop/scripts repo that has the vendored yarn (plus other common deps like TS), and include it as a submodule in all repos?

[shiftkey]

It's something that interests me, but for the moment I'd like to follow the rule of 3 to identify what's actually needed in this hypothetical situation.