github-copilot-cli: preserve args for local-type MCP servers

forCopilotFormat only checked for type == "stdio" to add back args,
missing the case where a server already has type = "local" (e.g. set
directly by a third-party module). This caused args to be absent in the
generated mcp-config.json, failing validation.

Also, running forCopilotFormat as an extraTransform meant it ran inside
transformMcpServer, which then filtered out args = [] in its cleanup
pass. Move forCopilotFormat to run after transformMcpServer so the
empty args list is preserved in the output.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

tests/modules/programs/github-copilot-cli/expected-mcp-integration-config.json

@@ -15,6 +15,7 @@
       "type": "local"
     },
     "fetch": {
+      "args": [],
       "command": "mcp-server-fetch",
       "tools": [
         "*"