Support and enforce peerDependencies

[eladb]

When a module's API includes types from another dependency, the right way to ensure that a consumer actually passes in objects that are semantically compatible is by ensuring that the object was instantiated from the exact same version, as long as it's semantically compatible.

The jsii compiler should emit warnings if a module's API includes types of other modules but those other modules are not defined also under peerDependencies of the package.json file.

We should also provide a tool to help "fix" package.json files by inspecting the jsii spec.

Related: #979

[eladb]

Dup aws/jsii#292