feat: add environment variables and docs

ref: N25B-352

src/robot_interface/utils/get_config.py

@@ -0,0 +1,32 @@
+import os
+from dotenv import load_dotenv
+
+load_dotenv()
+
+
+def get_config(value, env, default, cast=None):
+    """
+    Small utility to get a configuration value, returns `value` if it is not None, else it will try to get the
+    environment variable cast with `cast`. If the environment variable is not set, it will return `default`.
+
+    :param value: The value to check.
+    :type value: Any
+    :param env: The environment variable to check.
+    :type env: string
+    :param default: The default value to return if the environment variable is not set.
+    :type default: Any
+    :param cast: A function to use to cast the environment variable. Must support string input.
+    :type cast: Callable[[Any], Any], optional
+
+    :return: The value, the environment variable value, or the default.
+    :rtype: Any
+    """
+    if value is not None:
+        return value
+
+    env = os.environ.get(env, default)
+
+    if cast is None:
+        return env
+
+    return cast(env)