test: restructure tests (#2444)

unit, api, wallets
* only run test-api for migration

tests/regtest/conftest.py

@@ -0,0 +1,17 @@
+import pytest_asyncio
+
+from .helpers import get_hold_invoice, get_real_invoice
+
+
+@pytest_asyncio.fixture(scope="function")
+async def hold_invoice():
+    invoice = get_hold_invoice(100)
+    yield invoice
+    del invoice
+
+
+@pytest_asyncio.fixture(scope="function")
+async def real_invoice():
+    invoice = get_real_invoice(100)
+    yield {"bolt11": invoice["payment_request"]}
+    del invoice