BREAKING: replace custom build scripts with nix

General:
- Switched to yarn to better work with nix-based tooling
- Switched package system to use nix. This stops double dependencies and slow cloud compile times, while providing more compile/runtime support to the Nix project
- Removed container builder in favor of internal container tooling
- Package versions no-longer need to be SemVer compliant
- Removed "piston package spec" files, replaced with nix-flake based runtimes
- Exported nosocket and piston-api as packages within the nix-flake
- Removed repo container
- Switched docker building to nix-based container outputting
- Removed docker compose as this is a single container
- Removed package commands from CLI

Packages:
- Move bash, clojure, cobol, node, python2, python3 to new format
- Remainder of packages still need to be moved

v2 API:
- Removed "version" specifier. To select specific versions, use the v3 api
- Removed "/package" endpoints as this doesn't work with the new nix-based system

v3 API:
- Duplicate of v2 API, except instead of passing in a language name an ID is used intead.

api/default.nix

@@ -0,0 +1,28 @@
+{pkgs, ...}:
+with pkgs; {
+  package = mkYarnPackage {
+    name = "piston";
+    src = ./.;
+
+    yarnPreBuild = ''
+      mkdir -p $HOME/.node-gyp/${nodejs.version}
+      echo 9 > $HOME/.node-gyp/${nodejs.version}/installVersion
+      ln -sfv ${nodejs}/include $HOME/.node-gyp/${nodejs.version}
+      export npm_config_nodedir=${nodejs}
+    '';
+
+    pkgConfig = {
+      waitpid = {
+        buildInputs = [
+          gcc
+          gnumake
+          python3
+        ];
+
+        postInstall = ''
+        yarn --offline run install
+        '';
+      };
+    };
+  };
+}