feat: Add support for multiple plugins with a single ApisixConsumer

[nilimaomni]

Description

I want to use multiple auth mechanism in a single route which requires to create consumer with multiple auth plugin. This is possible via apisix admin api. Example:

curl http://localhost:9180/apisix/admin/consumers -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "username": "xyz",
    "plugins": {
        "hmac-auth": {
            "access_key": "ejncd934fie",
            "secret_key": "whrbkjndc239o",
            "validate_request_body": true
        },
        "key-auth": {
            "key": "auth-one"
        }
    }
}'

But for convenience I want to keep it in config file and want to create consumer via ApisixConsumer CRD. I want something like this:

kind: ApisixConsumer
metadata:
  name: jack
spec:
  authParameter:
      hmacAuth:
        value:
          access_key: "ejncd934fie"
          secret_key: "whrbkjndc239o"
          validate_request_body: true
      keyAuth:
        value:
          key: "auth-one"

It works for single plugin consumer But more than one schema (plugin config) is not supported, hence throwing error :

The ApisixConsumer "jack" is invalid: : Invalid value: "": "spec.authParameter" must validate one and only one schema (oneOf). Found 2 valid alternatives

Kindly add support for the above mentioned feature.