Fix INF2 example handler

[namannandan]

Description

Fix handler for Inferentia2 example to handle partial batches and calls to transformers-neuronx library api

Type of change

• Bug fix (non-breaking change which fixes an issue)

Feature/Issue validation/testing

• Successful manual test for 125m parameter variant of the opt model

$ cat sample_text.txt 
Today the weather is really nice and I am planning on
$ curl http://127.0.0.1:8080/predictions/opt-125m -T sample_text.txt 
Today the weather is really nice and I am planning on
going through some camping next weekend. I thought if I didn’t
wear rain gear on Saturday maybe I would have to wear a coat but
I am using my wet shoes

• Test for the 6.7b parameter variant of opt model [in progress]

$ cat sample_text.txt 
Today the weather is really nice and I am planning on
$ curl http://127.0.0.1:8080/predictions/opt-6.7b -T sample_text.txt 
Today the weather is really nice and I am planning on
spending the day in the park and riding my bike to the
store for ice cream. Then I will come home and study
more Spanish. It is raining and sunny here,

[HamidShojanazeri]

LGTM thanks @namannandan