Set up generator

[bknoles]

Adds a generator for installing a few necessary files for a React based inertia_rails project:

• An inertia.jsx pack file with CSRF set up that renders an Inertia app, and adds it into application.html.erb
• A controller, route, and React component for a "hello world!" inertia-fied page
• Adds the appropriate inertiajs packages via Yarn
• Stubbed, non-functional rake tasks for Vue and Svelte installs (we use React internally so we haven't built out these installers yet)

The task is run via:

./bin/rails inertia_rails:install:react
./bin/rails inertia_rails:install:vue # doesn't do anything yet
./bin/rails inertia_rails:install:svelte # doesn't do anything yet