Refactor and clean up grid previews

[nathanwoulfe]

Prerequisites

• I have added steps to test this contribution in the description below

Description

After merging #9242, I had a closer look at the grid preview, which lead to a closer look at the grid property editor, which lead to a chunk of refactoring and cleanup, which lead to this PR.

• removes all references to usky in the markup and CSS
• removes gridview.less (not used after removing usky refs)
• standardises grid layout/row previews in editor, prevalues and overlays
• adds umb-icon directive
• refactors to add umb-grid-preview-- namespace
• general UI improvements (these views hadn't been substantially reviewed since v7)

To test, verify the UI works correctly and is consistent across the different views (grid editor, prevalues, row and layout overlays), can add/remove columns in a layout/row, can delete rows/columns, etc - all existing behaviours should continue to work fine, these changes are UI only.

Prevalues / datatype config

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After:

Layout config overlay

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Row config overlay

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After:

[umbrabot]

Hi there @nathanwoulfe!

Thanks for the contribution here and apologies if it has been a while since you heard from us. We have been in the very fortunate position of having lots of work to do. With this in mind, we are writing to let you know that with the release of the Long Term Support (LTS) version, 8.18, we have now moved into the support phase of Umbraco 8. You can read all about that here but to surmise, we will be keeping Umbraco 8 safe and well by releasing patching for security or regression issues if they arise but no longer will we do that for bug fixes. The same is still true for features, although we stopped merging those some time ago.

We'd love for you to keep contributing and while we are not able to merge this to Umbraco 8, if this is still something you'd like to see in Umbraco 9, please take a look and either create an issue to say so or find an issue that already exists. We'll be happy to give you some input around how you can adjust your pull request to target Umbraco 9. Even better, it might be something that Umbraco 9 already does or has. In which case, enjoy!

Once again, a huge thank you for the time you have spent working with us.

#H5YR
Your friendly Umbraco GitHub bot 🤖 🙂