[vulkan] Convolution op cleanup (#60759)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/60759
Remove unused convolution implementations and refactor convolution op code to make this file easier to maintain.
Test Plan:
Test vulkan ops:
```
cd ~/fbsource
buck build -c ndk.custom_libcxx=false -c pt.enable_qpl=0 //xplat/caffe2:pt_vulkan_api_test_binAndroid\#android-arm64 --show-output
adb push buck-out/gen/xplat/caffe2/pt_vulkan_api_test_binAndroid\#android-arm64 /data/local/tmp/vulkan_api_test
adb shell "/data/local/tmp/vulkan_api_test"
cd -
```
Reviewed By: IvanKobzarev
Differential Revision: D28724592
fbshipit-source-id: cb509fa1cd68089f78188bfb3c866aabc9b0cbdb
