The node implementation of `getDefaultTranslationsFactory` is inefficient

[charlespwd]

https://github.com/Shopify/liquid-language-server/blob/main/packages/node/src/index.ts#L67-L92

Even though the body and parsed JSON is cached, we're re-reading the file contents on every call to runChecks.

A smarter approach would be to start a file watcher (presumably with chokidar to avoid weird node.js macos/windows file watch issues) and invalidate the cached value on file system file change.