Add "Depended On By" section to Module inspector pane

[broofa]

In the "Modules" pane, we should add a "Depended On By" section that lists the modules that directly depend on the currently selected module.

Use Case

It's not uncommon for me to be looking at a dependency graph and notice something unusual about a module that causes me to wonder why it's part of the dependency tree. For example:

• Go to https://npmgraph.js.org/?q=react-hot-loader
• Set "Include devDependencies" to "On"
• Find and select the core-js module.
• Notice the rather alarming deprecation warning for core-js:

At this point, it'd be really nice to see how/why this deprecated module is still part of the react-hot-loader dependency tree. But there's no simple way of doing that. Oh, sure, we highlight the arrows from dependees that lead to core-js when you have it selected, but this graph is sufficiently complex that it's difficult to discern which modules those are, exactly.