Add codefix to generate types for untyped module

[ghost]

Fixes #25746

Adds a new codefix, also in fixCannotFindModule.ts since it is similar to the fix for installing an @types package and won't trigger if an @types package exists. This fix requires the value of the module and inspects the resulting value.

We don't want to call require (which can execute arbitrary code) during regular code fixes, so instead we generate a command which can be executed in a separate process. I put this in typingsInstaller since that's currently our only separate process, and I didn't want to create a third process.
typingsInstaller uses inspectValue.ts, which is designed to not require TypeScript (and not pull more code into typingsInstaller such as textChanges), and just produce a JSON representation of the required value. That is then passed to generateTypes.ts which actually converts that to an AST and renders.

The function generateTypesForModule is currently internal, but could be publicly exposed and made to be the implementation of dts-gen, which its code is based on.