Allow timestamp type to be inferred when using schema inference

[colinhicks]

Is your feature request related to a problem? Please describe.
Currently schemas that are tagged with timestamp metadata are inferred with the bigint type. For example, when schema inference is used when the input topic schema contains a timestamp-tagged Avro record field:

{
  "name": "XYZ",
  "type": {
    "connect.name": "org.apache.kafka.connect.data.Timestamp",
    "connect.version': 1,
    "logicalType": "timestamp-millis",
    "type": "long"
  }
}

... a respective stream created using schema inference would use BIGINT for the XYZ column.

Describe the solution you'd like
Schemas tagged with timestamp metadata should be inferred with the ksqlDB timestamp type.