Prompt Learning Pipeline Parallel
# What does this PR do ?

1. Adds pipeline parallel capability  to GPT p-tuning and prompt tuning
2. makes prompt learning methods compataible with GPT models trained with amp O2, 
3. switches to smaller gpt model and datasets for CI test, adding tp and pp tests

**Collection**: BigNLP

# Changelog 
- Updated MegatronGPTPromptLearning class
- Updated prompt learning config
- Moved all reduce gradient method to base megatron model
- Updated prompt learning CI tests

# Usage

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**PR Type**:
- [x] New Feature
- [ ] Bugfix
- [ ] Documentation

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# Additional Information
* Related to # (issue)
