[PERF-303] Integer XBlocks/XModules into the static asset pipeline.

This PR, based on hackathon work from Christina/Andy, implements a way to discover all installed XBlocks and XModules and to enumerate their public assets, then pulling them in during the collectstatic phase and hashing them.  In turn, the methods for generating URLs to resources will then returned the hashed name for assets, allowing them to be served from nginx/CDNs, and cached heavily.

This is a clone (copy) of CSMH's declaration and methods with an added
id of UnsignedBigInAutoField

We should be able to delete the save_history code, but needs testing.

Add error logging when capa failures happen

Put StudentModuleHistory into its own database

Bump out the primary key on CSMHE

This gives us a gap to backfill as needed.
Since the new table's pk is an unsigned bigint, even for people who don't
consolidate CSMH into CSMHE, the lost rows are unlikely to matter.

Remove StudentModuleHistory cleaner

Please note that this is a squshed commit and the work of:
Symbolist, macdiesel, nedbat, doctoryes, muzaffaryousaf and muhammad-ammar

TNL-3137

TNL-3137

TNL-3137

TNL-2487

TNL-2465