🚨 🚨 🚨 Fix CvT parameter initialization 
Author: mathieujouffroy
Pull request: yes

# What does this PR do?

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This PR aims to rectify the difference in parameter initialization between the HF implementation and the original implementation (microsoft).

- Initializes torch dense layer weights with trunc_normal instead of normal.
- Initializes cls_token with trunc_normal


## Before submitting
- [ ] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
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## Who can review?

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As [discussed](https://github.com/huggingface/transformers/pull/18597#issuecomment-1271354673) @amyeroberts here's the PR regarding the changes for the CvT pytorch model 😊


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Models:

- albert, bert, xlm: @LysandreJik
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Library:

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Documentation: @sgugger

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