Fix list to use dividers the same way tree/table do.

[okratitan]

Description:

Make list reuse dividers and place them correctly rather than using a border on list items.

Checklist:

• Tests included.
• Lint and formatter run with no errors.
• Tests all pass.

Where applicable:

• Public APIs match existing style.
• Any breaking changes have a deprecation path or have been discussed.

[andydotxyz]

I think this breaks some size calculations, I can no longer access the bottom of the list.

[andydotxyz]

Image for the comment - the demo should have 1000 items, but alas:

[andydotxyz]

Also I noticed that list items are smaller than tree and table items again - we had this lined up nicely a while back

[okratitan]

Fyne Demo accessing the last item in the list:

List and tree items being the same size not smaller:

Are you sure you are up today with the PR? Is something else breaking it? It passes all test and works and looks as it should here

[andydotxyz]

This is up to date - it appears that it's harder to repliate than I thought - but the issue is in there somewhere.
Scroll related it seems. Steps to replicate:

• Scroll to end of list bu dragging the scrollbar
• Using scroll wheel drag up around half a screen
• Scroll down again
• Notice that it no longer reaches the end of the list
• Repeat and you will see the error is cumulative.

[andydotxyz]

Also I noticed that list items are smaller than tree and table items again - we had this lined up nicely a while back

Apologies, this is not an issue - I must have been comparing develop where it is still broken.

[andydotxyz]

With the height fixed it looks like the indicators are now too short...