[Remove Vuetify from Studio] Top-level buttons in Channels

[RONAK-AI647]

Summary

Solves Issue #5218

Removed Vuetify that used VBtn from the following buttons in Channels:
That is <NewChannel> and < NewCollection> and used KButton to replace them which is a KDS component.

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References

1. https://design-system.learningequality.org/buttons/ [ The buttons are supposed to be like this]
2. https://design-system.learningequality.org/kbutton [ the KButton format]

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Reviewer guidance

Upadted VBtn with KButton
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[RONAK-AI647]

@MisRob @bjester , Take a look

[MisRob]

Thank you @RONAK-AI647! Code changes make sense and I confirm that clicking buttons works as expected.

For next time, would you upload screenshots you took after your changes? It helps reviewers to quickly get a sense of changes, and also understand that authors tested them. There's no need to re-upload images from the issue, we can find it easily there.

[RONAK-AI647]

My bad @MisRob , they looked same , like no new UI change was there , so I thought to use the issue screenshot which had arrows , so others who visit the pr will quickly understand we are talking about which buttons . I will take care next time.

[MisRob]

No problem @RONAK-AI647. There are some minor expected changes, but it takes a very very detailed eye to spot it :))