Grouped convolution backward weight special vector size loads

[bartekxk]

Proposed changes

Grouped convolution backward weight special vector size loads to support different size of vector loads

Checklist

Please put an x into the boxes that apply. You can also fill these out after creating the PR. If you're not sure, please don't hesitate to ask.

• I have added tests relevant to the introduced functionality, and the unit tests are passing locally
• I have added inline documentation which enables the maintainers with understanding the motivation
• [x ] I have removed the stale documentation which is no longer relevant after this pull request
• [x ] (If this change is user-facing) I have added release notes which provide the end users with a brief summary of the improvement from this pull request
• [x ] I have run clang-format on all changed files
• [x ] Any dependent changes have been merged

Discussion

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