Install modules from Puppetfile to <project>/.modules

[lucywyman]

Use Case

We should install modules to the .modules directory of a project. This directory should always be on the module path after any user-specified directories but before the bundled content directory.

• This should only get installed to this using bolt modules install.
• bolt puppetfile install should still install to the front of the modulepath
• We should add a new feature to bolt project migrate
  • Clear out existing modules
  • Give users the opportunity to specify modules specified in the project. For the rest of the project lifecycle, modules in modules get installed to .modules/.
  • If users do module add without a modules in bolt-project.yaml, we error
• This should be released once bolt modules install and bolt modules add are added.