Drop merged GraphQL schema for split files

Relay no longer needs a single merged schema.graphql: each project in
relay.config.json now reads the split graphql/*.graphql files directly
via `schema` (base.graphql) plus `schemaExtensions`. gqlgen already
consumed the split files, so the merge step only fed Relay and the
optional IDE GraphQL extension.

Remove the merge machinery (contrib/merge-graphql-schema.sh, the
RELAY_SCHEMAS make rules, and the gitignore entry) and drop the
graphql-config files (apps/trust/graphql.config.yml and the root
package.json graphql field); the Relay extension provides schema-aware
language features from relay.config.json on its own.

relay-compiler keeps generated artifacts in sync (stale ones are
removed automatically), so the relay npm script just runs the local
relay-compiler and the make target delegates to it.

Signed-off-by: Émile Ré <emile@probo.com>

relay.config.json

@@ -10,7 +10,8 @@
   },
   "projects": {
     "core": {
-      "schema": "pkg/server/api/console/v1/schema.graphql",
+      "schema": "pkg/server/api/console/v1/graphql/base.graphql",
+      "schemaExtensions": ["pkg/server/api/console/v1/graphql"],
       "language": "typescript",
       "noFutureProofEnums": true,
       "output": "apps/console/src/__generated__/core",
@@ -25,7 +26,8 @@
       }
     },
     "iam": {
-      "schema": "pkg/server/api/connect/v1/schema.graphql",
+      "schema": "pkg/server/api/connect/v1/graphql/base.graphql",
+      "schemaExtensions": ["pkg/server/api/connect/v1/graphql"],
       "language": "typescript",
       "noFutureProofEnums": true,
       "output": "apps/console/src/__generated__/iam",
@@ -40,7 +42,8 @@
       }
     },
     "trust": {
-      "schema": "pkg/server/api/trust/v1/schema.graphql",
+      "schema": "pkg/server/api/trust/v1/graphql/base.graphql",
+      "schemaExtensions": ["pkg/server/api/trust/v1/graphql"],
       "language": "typescript",
       "noFutureProofEnums": true,
       "customScalarTypes": {