b5146

llama : recognize IBM Granite 3.3 FIM tokens (#12988)

The Granite's FIM tokens are very similar to Qwen's; it's just that
they use underscore instead of a dash. So <fim_middle> for example
instead of <fim-middle>.

Opening up tokenizer_config.json in ibm-granite/granite-3.3-8b-base
shows:

```
    "<fim_prefix>",
    "<fim_middle>",
    "<fim_suffix>",
    "<fim_pad>",
    ...
    "<reponame>",
```