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.

runtimes/.scaffold.nix

@@ -0,0 +1,65 @@
+{pkgs, piston, ...}:
+let
+    # Put your package here, preferibly from nixpkgs.
+    pkg = pkgs.%RUNTIME%; # this may be incorrect - it is guessed
+in piston.mkRuntime {
+    # Name of the language implemented by this runtime
+    language = "%LANGUAGE%";
+    
+    # The version of the language
+    # Usually this is specified on the package
+    version = pkg.version;
+
+    # Name of the runtime
+    # This line should be kept if the runtime differs from the language
+    runtime = "%RUNTIME%";
+
+    aliases = [
+        # Put extensions in here, and other common names
+        # Example:
+        # "js"
+        # "node-javascript"
+    ];
+
+
+
+    # This is the lines of a shell script to compile source code.
+    # Arguments passed to this script are all the provided source files
+    # The CWD of this script is a temp directory for a job
+    #
+    # If the language only supports JIT compiling, simply remove this line
+    # See ./python3.nix and ./node-javascript.nix for examples
+    #
+    # No shebang needs to be added to this - that is done automatically.
+    compile = ''
+    ${pkg}/bin/%RUNTIME% --compile "$@"
+    '';
+
+    # This is the lines of a shell script to evaluate a file at $1
+    # The remaining arguments are the arguments to launch the application with
+    # The CWD of this script is a temp directory for a job
+    #
+    # If the compile stage is used, $1 still contains the name of the source file.
+    # It is up to your script to determine the filename of the emitted binary
+    #
+    # No shebang needs to be added to this - that is done automatically.
+    run = ''
+    ${pkg}/bin/%RUNTIME% "$@"
+    '';
+
+    # Specify a list of tests.
+    # These should output "OK" to STDOUT if everything looks good
+    tests = [
+        (piston.mkTest {
+            files = {
+                "test.js" = ''
+                    console.log("OK");
+                '';
+            };
+            args = [];
+            stdin = "";
+            packages = [];
+            main = "test.js";
+        })
+    ];
+}