Add user:pass Basic auth mode for API-key connectors

The API-key connection transport could present a key as a Bearer token,
an x-api-key header, a custom scheme (SSWS/Token), or HTTP Basic with an
empty password (Cursor). None of these can carry a real password, which
providers such as ClickHouse Cloud (keyId:keySecret) and Langfuse
(publicKey:secretKey) require.

Add a fourth mode, APIKeyBasicAuthUserPass, that base64-encodes the
stored "username:password" credential verbatim into Authorization: Basic.
SetBasicAuth cannot express this -- it re-appends a ":" and corrupts the
credential. The mode is wired generically through the registry and the
create-connector resolver and is mutually exclusive with the other
API-key auth modes.

Signed-off-by: Aurélien Sibiril <81782+aureliensibiril@users.noreply.github.com>

pkg/server/api/console/v1/connector_resolvers.go

@@ -41,10 +41,11 @@ func (r *mutationResolver) CreateAPIKeyConnector(ctx context.Context, input type
 		Provider:       input.Provider,
 		Protocol:       coredata.ConnectorProtocolAPIKey,
 		Connection: &connector.APIKeyConnection{
-			APIKey:    input.APIKey,
-			Header:    r.providerRegistry.APIKeyHeader(input.Provider),
-			BasicAuth: r.providerRegistry.APIKeyUsesBasicAuth(input.Provider),
-			Scheme:    r.providerRegistry.APIKeyAuthScheme(input.Provider),
+			APIKey:            input.APIKey,
+			Header:            r.providerRegistry.APIKeyHeader(input.Provider),
+			BasicAuth:         r.providerRegistry.APIKeyUsesBasicAuth(input.Provider),
+			BasicAuthUserPass: r.providerRegistry.APIKeyUsesBasicAuthUserPass(input.Provider),
+			Scheme:            r.providerRegistry.APIKeyAuthScheme(input.Provider),
 		},
 	}