ReactPress should be less strict/dependent on the packaging framework used

[BlairCooper]

Currently ReactPress is dependent on how a "standard" CRA or Vite application is packaged. Specifically on the requirement for a "build" or "dist/assets" folder.

ReactPress should be able to detect which folder the application resides in be it the root of the app folder, or the build, dist or dist/assets folders. Further, ReactPress should attempt to detect the entry point if it can't be determined from something like the asset-manifest.json file. For example, look for index*.js, main*.js, and bundle*.js.

Possible allow configuration options to specify the subfolder the application resides in, and the entry point file.

These changes would allow for different frameworks and configurations to be utilized when building the React app.