TH assets

[ali-abrar]

The old approach to the generated static assets module was designed to avoid template haskell. Since that's no longer a requirement, we no longer have to take a promoted-strings approach. This PR replaces the old static @"some/path" approach with $(static "some/path) using TH.

The old approach of statically generating a map of all the static assets also meant that any static files added while ob run was running wouldn't be usable until the ob run process was terminated and restarted. This PR includes an implementation of static for the ob run case that allows files to be added and accessed by ob run without restarting (hence the updates to obelisk-command).

I have:

• Based work on latest develop branch
• Followed the contribution guide
• Looked for lint in my changes with hlint . (lint found code you did not write can be left alone)
• Run the test suite: $(nix-build -A selftest --no-out-link)
• Updated the changelog
• (Optional) Run CI tests locally: nix-build release.nix -A build.x86_64-linux --no-out-link (or x86_64-darwin on macOS)