[@mantine/core] FloatingIndicator: fix translate calculations

[lamualfa]

Descriptions

The borderTopWidth & borderLeftWidth from parent & target should added to translate calculation because getBoundingClientRect included that on calculation.

Before

After

It's a little bit difficult to see the difference unless you use wider border width.

Notes

• I reuse toInt helper from ScrollArea utils to convert computed style to int. That helper should be on more generic folder/file other than ScrollArea. I'm not sure where to put it. This refactor must be in different commit.

[rtivital]

Thanks!