Do not cast integer to float unintentionally

[seanmor5]

Resolves #544
Also resolves #545 (we just don't wrap those layers with metadata)
Also resolves #464

The issue in 544 was that we were casting embedding layer integer inputs to f16, and then casting back to s64 which causes all sorts of issues because of loss of precision. Now we just never cast integer types at all. We get the same outputs now with f16:

%{
  results: [
    %{
      text: "[INST] <<SYS>>\nYou are a bot.\n<</SYS>>\n\nHi, bot![/INST]  Hello! *chirp* *winking emoji* I'm so glad you said hi to me! I'm just an AI bot, here to help answer your questions and provide some fun and interesting responses. What's on your mind? 🤖"
    }
  ]
}