vite_rails: Improve default deployment and dev enviroment support

[bamnet]

Rails 7.2+ ships with features like the ability to generate a devcontainer for development, Github Action to run tests and Rails 8 will ship with Kamal configured by default for deployment.

It would be helpful if vite_rails integrated into these systems automatically or (as a fallback) documented what steps users need to take in order to work with these new defaults.

At a first pass, I ran into trouble with:

• Github Action tests where vite wasn't installed (solved by manually adding run: npm install)
• Kamal, where npx wasn't installed
• Devcontainers - untested.

There are some pointers in the existing docs, like a dependency on npx and some notes about devcontainers port forwarding, but I think it would be helpful to have very clear steps for Rails users as part of the vite_rails setup docs.

For example, I'm not sure if I should actually be running npm install in my Github Action or if there's a bug somewhere in vite:install_dependencies or other hooks which should automatically install the deps.