Improvements to components:dev:test

[taylorreece]

This commit adds two additional features to prism components:dev:test:

• An npm run build is now automatically issued when the subcommand is run. It's far to easy to forget to build prior to testing. This ensures that you build before running a test. You can opt out of the build behavior with --no-build.
• You can now choose to write the results of your action's step to a file. If your action returns a JSON-serializable object, it's serialized to JSON and written out. If it returns a string, that string is written out. If it returns a Buffer or a binary file (png, pdf, etc), those are also written out properly. This lets you verify quickly that your action returns the structure of data that you'd expect it to. You can choose to write out step result data with the flag --output-file my-file.png (replacing the file name with whatever makes sense for you).

Additionally, some functionality (like spawning child processes or fetching step results) were abstracted into utility functions so multiple subcommands could use them.

[hipplej]

[ryanwersal]

LGTM 👍 Thanks!