**Changes:**
- New option flags `--pax-split-qkv` and
`--te-qkv-layout={qkv_packed,kv_packed}` for identifying QKV layouts for
both the Pax source and TE target. Default behavior without new flags
remains unchanged.
- New option flag `--use-gated-activations` to support gated GELU in
LLaMa2.
- Bias terms are omitted from the checkpoint map when `--weight-only` is
used.

**Notes:**
- Changes are verified with a 70b LLaMa2 checkpoint previously converted
with @mingxu1067's hard-coded LLaMa2-only converter script.
```
python converter/main.py \
    --input-path=<...> \
    --output-path=<...> \
    --fw=pax --direction=fw2te \
    --num-of-layer=80 \
    --num-of-head=64 \
    --head-dim=128  \
    --mlp-intermediate-dim=28672 \
    --kernel-chunk-size=512 \
    --weight-only \
    --use-gated-activations \
    --pax-split-qkv \
    --te-qkv-layout=kv_packed
```

---------

Signed-off-by: Alp Dener <[email protected]>
Co-authored-by: ashors1 <[email protected]>