Allow LSPAssetsPlugin to Load Assets from Module

[KetanReddy]

Problem

Currently, the CLI's LSPAssetsPlugin plugin only allows users to specify a file path to load XLRs into the LSP. This requires some unfriendly initialization of the plugin when passing XLR enabled packages as you would need to do something like the below to initialize it:

new LSPAssetsPlugin({
        path: path.join(require.resolve('@player-ui/types'), '..')
      })

Given that the entrypoint for each module can be different, the added effort of finding how many levels to go up from the entrypoint to get to the xlr folder in the module may require some trial and error.

Proposed Solution

If we embrace subpath exports (which are supported back through node 14) to allow the manifest.js file in the generated XLR folder to be accessed via a subpath, the package author can easily expose the XLR location and the integration author can access it in a standard way without having to know how the original package is setup. Example:

In the XLR enabled library's package.json

...
"exports": {
    "./xlr": "./dist/xlr/manifest.js"
  },
...

In the CLI Preset of the integrating application

new LSPAssetsPlugin({
        path: require.resolve('@player-ui/types/xlr')
      })

Work to Do

• Update Player's Bazel rules to generate a subpath export for XLR enabled packages
• Update LSPAssetsPlugin to allow loading XLRs via Module or Make a new plugin for specifically loading XLRs via module