RootCanal: legacy advertising PDU updates

- Remove SCAN_RSP from legacy advertising PDU types,
  SCAN_RSP is represented by the ScanResponse packet
- Perform explicit conversion of advertising types between
  bluetooth::hci and model::packets instead of casting
  values
- Use LeAdvertisingReportRawBuilder instead of a raw
  packet builder

Test: gd cert + manual
Change-Id: Ia9ae155f5106f964f5c16779edaea8baf712b9b0