bug: API-driven standalone mode does not properly handle resources with duplicate IDs

[bzp2010]

Current Behavior

When two services with the same ID are entered (in fact, any resource), the Admin API accepts the input.
When fetching resources via GET, resources with the same ID are output.

Expected Behavior

Only one of multiple duplicate ID resources should be accepted. And reject the input if it is completely unprocessable, e.g., both ID and modifiedIndex are the same.

Error Logs

No response

Steps to Reproduce

{
    "ssls_conf_version": 0,
    "consumer_groups_conf_version": 1,
    "protos_conf_version": 1,
    "secrets_conf_version": 1,
    "plugin_metadata_conf_version": 0,
    "services": [
        {
            "modifiedIndex": 4,
            "desc": "desc",
            "name": "service1",
            "upstream": {
                "scheme": "https",
                "nodes": [
                    {
                        "host": "httpbin.org",
                        "weight": 100,
                        "port": 443
                    }
                ]
            },
            "id": "6e899c1108b88e75d4887b85f9a62c26d9571739",
            "hosts": [
                "example1.com",
                "example2.com"
            ]
        },
        {
            "modifiedIndex": 1,
            "id": "6e899c1108b88e75d4887b85f9a62c26d9571739",
            "name": "service1",
            "hosts": [
                "example1.com",
                "example2.com"
            ],
            "upstream": {
                "scheme": "https",
                "nodes": [
                    {
                        "host": "httpbin.org",
                        "port": 443,
                        "weight": 100
                    }
                ]
            }
        },
        {
            "modifiedIndex": 1,
            "id": "45d48919804fadc2db9d0180a65fe0ee0a8ddf9a",
            "name": "service2",
            "upstream": {
                "scheme": "https",
                "nodes": [
                    {
                        "host": "httpbin.org",
                        "port": 443,
                        "weight": 100
                    }
                ]
            }
        }
    ],
    "upstreams_conf_version": 0,
    "routes_conf_version": 0,
    "services_conf_version": 6,
    "plugin_configs_conf_version": 1,
    "consumers_conf_version": 0,
    "global_rules_conf_version": 0,
    "stream_routes_conf_version": 0
}

#1 update
curl http://localhost:19180/apisix/admin/configs -H "x-api-key: edd1c9f034335f136f87ad84b625c8f1" -XPUT --data '{"ssls_conf_version":0,"consumer_groups_conf_version":1,"protos_conf_version":1,"secrets_conf_version":1,"plugin_metadata_conf_version":0,"services":[{"modifiedIndex":4,"desc":"desc","name":"service1","upstream":{"scheme":"https","nodes":[{"host":"httpbin.org","weight":100,"port":443}]},"id":"6e899c1108b88e75d4887b85f9a62c26d9571739","hosts":["example1.com","example2.com"]},{"modifiedIndex":1,"id":"6e899c1108b88e75d4887b85f9a62c26d9571739","name":"service1","hosts":["example1.com","example2.com"],"upstream":{"scheme":"https","nodes":[{"host":"httpbin.org","port":443,"weight":100}]}},{"modifiedIndex":1,"id":"45d48919804fadc2db9d0180a65fe0ee0a8ddf9a","name":"service2","upstream":{"scheme":"https","nodes":[{"host":"httpbin.org","port":443,"weight":100}]}}],"upstreams_conf_version":0,"routes_conf_version":0,"services_conf_version":6,"plugin_configs_conf_version":1,"consumers_conf_version":0,"global_rules_conf_version":0,"stream_routes_conf_version":0}'

#2 get
curl http://localhost:19180/apisix/admin/configs -H "x-api-key: edd1c9f034335f136f87ad84b625c8f1"

Environment

• APISIX version (run apisix version): master
• Operating system (run uname -a): N/A
• OpenResty / Nginx version (run openresty -V or nginx -V): N/A
• etcd version, if relevant (run curl http://127.0.0.1:9090/v1/server_info): N/A
• APISIX Dashboard version, if relevant: N/A
• Plugin runner version, for issues related to plugin runners: N/A
• LuaRocks version, for installation issues (run luarocks --version): N/A