Create option to disable webpack-dev-server and compile webpack to file system

Currently we utilize webpack-dev-server in the GDK which compiles our frontend assets and retains them in memory so that when developers make changes to our frontend code, it can be quickly re-compiled and served.

However, webpack-dev-server takes up a LOT of memory, and there are many legitimate cases where one may prefer to only compile assets on-demand without retaining them in memory.

Deliverable description

• Create an option, controlled by an environment variable (e.g. DEV_SERVER_STATIC=true), which will disable webpack-dev-server and instead run webpack to compile assets to disk, then watch for changes in the filesystem, and run webpack again on-demand to re-compile as necessary.
• Ensure these assets are compiled into a transient directory, and ignored by source control
• Ensure that these assets are cleaned up properly when the process is terminated, and that switching back to webpack-dev-server does not cause any problems with cached assets
• Document the trade-offs of using this option versus webpack-dev-server and cite examples of when one may want to use this (e.g. the GEO team which requires multiple copies of the GDK to run at once).