feat(build): Add WORKSPACE configuration for Bazel

This sets up Haskell & Nix rules in the workspace.

WORKSPACE

@@ -0,0 +1,39 @@
+# -*- mode: bazel; -*-
+#
+# This workspace configuration loads all Bazel rule sets that need to
+# be available in the entire repository.
+
+workspace(name = "tazjin_monorepo")
+
+# SECTION: Nix
+
+local_repository(
+  name = "io_tweag_rules_nixpkgs",
+  path = "third_party/bazel/rules_nixpkgs",
+)
+
+load("@io_tweag_rules_nixpkgs//nixpkgs:nixpkgs.bzl", "nixpkgs_local_repository", "nixpkgs_package")
+
+# SECTION: Haskell
+
+local_repository(
+  name = "io_tweag_rules_haskell",
+  path = "third_party/bazel/rules_haskell",
+)
+
+load(
+    "@io_tweag_rules_haskell//haskell:repositories.bzl",
+    "haskell_repositories"
+)
+
+haskell_repositories()
+
+load(
+    "@io_tweag_rules_haskell//haskell:nixpkgs.bzl",
+    "haskell_register_ghc_nixpkgs",
+)
+
+haskell_register_ghc_nixpkgs(
+    version = "8.6.4",
+    repositories = { "nixpkgs": "default.nix" }
+)