[PR-915] - Fix responses pricing

[phatvo9]

What

Fix responses pricing

How

• Handle usage of last chunk of chat_completions and responses in both stream and non stream.
• Add test cases.
• Raise error if usage reports 0 input and 0 output tokens.

[github-actions]

Package	Line Rate	Health
clarifai	45%	❌
clarifai.cli	44%	❌
clarifai.cli.templates	33%	❌
clarifai.client	67%	➖
clarifai.client.auth	67%	➖
clarifai.constants	100%	✔
clarifai.datasets	100%	✔
clarifai.datasets.export	80%	✔
clarifai.datasets.upload	75%	➖
clarifai.datasets.upload.loaders	37%	❌
clarifai.models	100%	✔
clarifai.modules	0%	❌
clarifai.rag	72%	➖
clarifai.runners	52%	➖
clarifai.runners.models	61%	➖
clarifai.runners.pipeline_steps	41%	❌
clarifai.runners.pipelines	70%	➖
clarifai.runners.utils	63%	➖
clarifai.runners.utils.data_types	72%	➖
clarifai.schema	100%	✔
clarifai.urls	60%	➖
clarifai.utils	60%	➖
clarifai.utils.evaluation	67%	➖
clarifai.workflows	95%	✔
Summary	62% (8364 / 13483)	➖

Minimum allowed line rate is 50%

[luv-bansal]

LGTM