Improve UX in build artifacts browser

This improves UX in build artifacts browser, and makes it more consistent with repository tree browser we already have.

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Before:

![ux_artifacts_before](/uploads/9869ff74afd5e6636f0df81c7823fb6f/ux_artifacts_before.png)

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After:

![ux_artifacts_after](/uploads/cdb68925f4489bb852fd701870e6d6a0/ux_artifacts_after.png)

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It is easier to click on a file/directory entry now, because we don't need to click on a entry's basename (that can be really short, like `..` parent directory). We also show `Compressed to` size that indicates how much storage does this entry really consume.

Row for an entry is also highlighted on hover and we do not have Download button (clicking on a file row / file basename is enough to download a file).

Closes #10242 

See merge request !2477