Dependent package errors should be more actionable

[mikrostew]

Repro

When running a package binary, if node_modules doesn't exist, or if one of the dependencies is missing (or at least the package.json is missing) you get this error:

$ ember serve
Notion error: Could not read dependent package info: Could not read package info: No such file or directory (os error 2)

But that doesn't tell the user what the actual problem is, or what to do about it.

Improvements

I think we can do a couple things better for this:

1. If dependencies are not installed at all (no node_modules folder), tell the user to install dependencies
2. If reading some dependency fails, provide info about which dependency failed (i.e. the path)

[charlespierce]

I believe this is actually fixed. First, we don't read dependency package.json files any more at all, and second, if node_modules isn't there when we try to run a binary (e.g. ember), we will show:

Volta error: Could not execute `/home/user/project/node_modules/.bin/ember`, the file does not exist.

Please ensure that all project dependencies are installed with `npm install` or `yarn install`