fix(Popover): correct fallback offset value to 8px when no arrow

[olros]

Summary

If the popover/tooltip/some other element depending on popover.ts is created with custom styles not using a ::before pseudo-element, the shift-param currently ends up being 0, even though the comment at the same line implies that it should default to 8px. This fixes that.

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• I have added a changeset (run pnpm changeset if relevant)

[changeset-bot]

🦋 Changeset detected

Latest commit: 5874af6

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 5 packages

Name	Type
@digdir/designsystemet-web	Patch
@digdir/designsystemet	Patch
@digdir/designsystemet-css	Patch
@digdir/designsystemet-types	Patch
@digdir/designsystemet-react	Patch

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[olros]

This should affect all floating elements using popover.ts I think, not sure if you want the changeset to specify all of them?

[eirikbacker]

Thanks for PR @olros 🤗 and good point! 🌟
This should probably instead calculate the value of a custom CSS property instead of always falling back to 8px, so it is possible to set this attribute to the size of the arrow. The popover.ts logic is used by both suggestions, dropdowns, tooltips, and popover components, as they all use the popover attribute. 8px arrows are not always the case, and we want all numbers to be configurable, so we can go ahead and iterate on this ☺️

[mimarz]

Thanks for PR @olros 🤗 and good point! 🌟 This should probably instead calculate the value of a custom CSS property instead of always falling back to 8px, so it is possible to set this attribute to the size of the arrow. The popover.ts logic is used by both suggestions, dropdowns, tooltips, and popover components, as they all use the popover attribute. 8px arrows are not always the case, and we want all numbers to be configurable, so we can go ahead and iterate on this ☺️

Thanks for the PR @olros!
A small change but it lays the seed for bigger improvements! Love it!

I have made a separate issue for work on the suggested improvements from @eirikbacker. We have a long list of features we are currently working on, and going into summer we are unsure when we'll get to have a look at this.

I've made an issue for it so anyone can have a go at it when there is time :)

#4940