Pulsar Java client's RecordSchemaBuilder doesn't provide any APIs to add nested records or Arrays for Avro and JSON type

### Search before asking

- [X] I searched in the [issues](https://github.com/apache/pulsar/issues) and found nothing similar.

### Version

Java Client(2.11.0)-->broker(2.11.0)
Broker instance OS: Amazon Linux 2023
Java App running OS : Windows 10

### Minimal reproduce step

- Using the RecordSchemaBuilder API I couldn't add any nested elements.
- Refer to the following code snippet which has nested records and array elements in the Schema definition.
- Using the record schema builder I couldn't find a way to add nested records or arrays.
- This applicable for both Avro as well as JSON. Hence request you to provide recommendations on how to achieve such use cases.

```
String avroSchemaDef= "{
"namespace": "my.com.ns",
"name": "myrecord",
"type": "record",
"fields": [{
"name": "uid",
"type": "int"
},
{
"name": "Product",
"type": "string"
},
{
"name": "options",
"type": {
"type": "array",
"items": {
"type": "record",
"name": "lvl2_record",
"fields": [{
"name": "item1_lvl2",
"type": "string"
},
{"name": "additional",
"type": {"type": "map", "values": "string"}},
{
"name": "item2_lvl2",
"type": {
"type": "array",
"items": {
"type": "record",
"name": "lvl3_record",
"fields": [{
"name": "item1_lvl3",
"type": "string"
},
{
"name": "item2_lvl3",
"type": ["string", "null"]
}, {
"name": "item_status",
"type": {
"name": "item_status",
"type": "enum",
"symbols": ["AVAILABLE", "OUT_OF_STOCK", "ONLY_FEW_LEFT"]
},
"default": "AVAILABLE"
}
]
}
}
}
]
}
}
}
]
}";
JSONObject schemaDefObj = new JSONObject(avroSchemaDef);
JSONArray fArray = schemaDefObj.getJSONArray("fields");
RecordSchemaBuilder recordSchemaBuilder = SchemaBuilder.record(schemaName);
for(int i=0;i

Start with the RecordSchemaBuilder and SchemaBuilder.record entry points mentioned in the issue, then trace how SchemaType and build(SchemaType) represent fields for Avro and JSON. Done should mean the builder offers a documented way to represent nested records and arrays for both schema types, with coverage for the nested example described here.

Written by the indexing model from the issue text.