Adds ability to pass chat_template_path argument into MaxText SFT, loading a separate chat_template from the tokenizer that's provided.

[copybara-service]

Adds ability to pass chat_template_path argument into MaxText SFT, loading a separate chat_template from the tokenizer that's provided.

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[codecov]

Codecov Report

❌ Patch coverage is 68.18182% with 7 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...text/input_pipeline/instruction_data_processing.py	75.00%	3 Missing and 2 partials ⚠️
src/maxtext/input_pipeline/hf_data_processing.py	0.00%	1 Missing and 1 partial ⚠️

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