In scratchpad only.
Closes #326.

Instead of `.cjs`; enough with this nonsense.

- don't rebuild the cli stuff when the frontend/backend changes
- make tests work again

This is not perfect but it works (and it is much faster).

For some reason I couldn't make `fflate-unzip` work with ESBuild, so
I've placed a copy and tweaked the exports.

This is a large build-time improvement, moreover we can get rid of a
lot of troublesome code regarding how to manage assets.

`esbuild` has proven a great tool so far.

Tested with both backends.

We still keep the CLI and the WASM backend on webpack, the idea is
to move them to esbuild in subsequent commits.

CLI should use a native Coq instead, it is super-slow.

We also disabled the `collab` and `ide-project` builds for now,
re-adding before merging hopefully.

The compatibility story with user .html pages needs to be revised,
IMHO as this is a foundation for the LSP backend this is the time to
drop support for some patterns we had in the past.

Borrowed from #275

We remove unused / browser `pp2HTML` and `richpp2HTML`, and we move
goal printing to coq-manager (for now), as to make the library purely
about `Pp.t -> Html` conversion.

We will reuse this library from vsCode (and maybe other projects), so
it makes sense to put it in its own directory, and maybe even at some
point in npm.

Along the way, we will cleanup some unused code, and add typing info
borrowed from #275

This should cleanup the root directory a bit; I've placed the cli
files inside `frontend`, but quite a few of these files should
eventually move to backend, as it seems to me that they functionality
that the "server" should provide, but we can do like this for now and
move things to `backend` as we see fit.

There is no longer @jscoq / @wacoq separation in pkgs.

Fixes #297.

Fixes #297.

Removed the backporting discrepancy in package builder.

Changed the calls from JS to be more similar.

We also move from hacks to a proper config object (which can be
properly created in a dynamic top-level context).

Also, note that we now use a ES6 map for the routes, this is more
convenient to add / remove elements than using the bare object.

This is rarely used live, and should allow us to make progress towards
the common protocol a bit more easy.

We reorganize jsCoq's source code as to be more modular, in particular
we start to place backend files under the `backend` directoy, and
frontend files under `frontend`.

Code as it now does work, note however that still quite a bit of work
is needed. In particular, the headless frontend should get its own
directory, the coq-jslib directory should go away, use more types,
etc...