feat: filter top-level resource with embed filter

This is enabled by adding `!inner` to the embedded resource

/projects?select=*,clients!inner(*)&clients.id=eq.12

This behaviour can be enabled by default with the config option

db-embed-default-join='inner'

Which saves the need for specifying `!inner` on every request.
If this is enabled, the previous behavior can be restored
per request by specifying `!left`  on the embedded resource.

/projects?select=*,clients!left(*)&clients.id=eq.12`

Tested on M20/02M/M2M relationships, views, RPC.

test/io-tests/test_io.py

@@ -440,6 +440,21 @@ def test_invalid_openapi_mode(invalidopenapimodes, defaultenv):
                 print(line)
 
 
+@pytest.mark.parametrize("invalidjointypes", FIXTURES["invalidjointypes"])
+def test_invalid_db_embed_default_join(invalidjointypes, defaultenv):
+    "Given an invalid db-embed-default-join, Postgrest should exit with a non-zero exit code."
+    env = {
+        **defaultenv,
+        "PGRST_DB_EMBED_DEFAULT_JOIN": invalidjointypes,
+    }
+
+    with pytest.raises(PostgrestError):
+        dump = dumpconfig(CONFIGSDIR / "defaults.config", env=env)
+        for line in dump.split("\n"):
+            if line.startswith("db-embed-default-join"):
+                print(line)
+
+
 def test_iat_claim(defaultenv):
     """
     A claim with an 'iat' (issued at) attribute should be successful.