Replaces the existing nodejs module end-to-end tests with integration tests that don't require preinstalled environmental dependencies.
- Moved the tests to the same file as the module they test
- Created a render_module utility function for rendering modules within tests
- Removed Node.js installation during CI setup
- Add Shell to Context to allow for tests to not run shell-specific code
- Create `Config` struct that is added to `Context` when initialized
- Read `~/.confg/starship.toml` during initialization (can be updated later to also look at `$XDG_CONFIG_HOME`)
- `Context` now has a method for creating modules. This allows us to provide modules with a reference to the configuration specific to that module