Support column rename with backwards compatibility

Avro allows one to rename a field and also retain the old name using an `alias` keyword like so:

```
// Sample avro schema with an aliased field
record FooTable {
// rename column old_bar to bar
string @aliases(["old_bar"]) bar;
// Other fields
}
```

While using avro schema to configure Pinot column names, is it possible to have a Pinot equivalent for this to allow easy column renaming? That way services still using the old column name still read and write using that old name.