feat(configuration): support multiple vaults in the configuration file (#6)

When multiple vaults are added to the configuration file, the script will prompt 
you to select one at runtime

tests/questions_test.py

@@ -0,0 +1,12 @@
+# type: ignore
+"""Test the questions class."""
+
+
+from obsidian_metadata._utils import Questions
+
+
+def test_vault_validation():
+    """Test vault validation."""
+    assert Questions._validate_vault("tests/") is True
+    assert "Path is not a directory" in Questions._validate_vault("pyproject.toml")
+    assert "Path does not exist" in Questions._validate_vault("tests/vault2")