Initialise the Auth(entic|oris)ation packages

Initialise the authentication/authorisation system packages and set up the
initial database migrations to set up the system.

* README.md: Add documentation on migrations
* gn3/auth/__init__.py: init package
* gn3/auth/authentication/__init__.py: init package
* gn3/auth/authorisation/__init__.py: init package
* gn3/migrations.py: provide migration utilities
* migrations/auth/20221103_01_js9ub-initialise-the-auth-entic-oris-ation-database.py:
  new migration
* tests/unit/auth/test_init_database.py: test new migration applies and rolls
  back as expected
* tests/unit/conftest.py: fixtures for unit tests
* yoyo.auth.ini: basic configuration for yoyo-migration for auth system
  migrations

1 files changed, 19 insertions, 0 deletions

diff --git a/migrations/auth/20221103_01_js9ub-initialise-the-auth-entic-oris-ation-database.py b/migrations/auth/20221103_01_js9ub-initialise-the-auth-entic-oris-ation-database.py
new file mode 100644
index 0000000..d511f5d
--- /dev/null
+++ b/migrations/auth/20221103_01_js9ub-initialise-the-auth-entic-oris-ation-database.py
@@ -0,0 +1,19 @@
+"""
+Initialise the auth(entic|oris)ation database.
+"""
+
+from yoyo import step
+
+__depends__ = {} # type: ignore[var-annotated]
+
+steps = [
+    step(
+        """
+        CREATE TABLE IF NOT EXISTS users(
+            user_id TEXT PRIMARY KEY NOT NULL,
+            email TEXT UNIQUE NOT NULL,
+            name TEXT
+        ) WITHOUT ROWID
+        """,
+        "DROP TABLE IF EXISTS users")
+]