Avoid ImageIcon use in more places, to preserve HiDPI icon resolution

[eirikbakke]

Replace various instances of 'new ImageIcon' with ImageUtilities.image2Icon in the platform module. This preserves HiDPI icons (e.g. SVG icons loaded by ImageUtilities) when relevant, and preserves rendering hints in ImageUtilities for bitmap icon scaling.

(These changes were made to ensure that the SVG icons added in #7463 actually show up in high resolution in various places.)

[matthiasblaesing]

Build from source - saw no change on "normal DPI", but changes look sane to me.

[eirikbakke]

@matthiasblaesing Thanks! Yeah, with no HiDPI scaling, icons should look identical.

[matthiasblaesing]

Yeah I suspected as much, I was between Comment and Approve. I eyeballed it, it builds, so it should work. If it does what it promises, would need someone with HiDPI setup.

[eirikbakke]

Verifying that things don't break on regular 1:1 scaling is probably good enough, since any visual difference is purely cosmetic. I've also tested the patch in my working IDE and NetBeans Platform app for the last 6 months, confirming no breakage.

(On Windows, I think scaling can be enabled from the "Display settings" control panel app whether or not the screen is actually HiDPI. On MacOS, every MacBook or Apple display is Retina i.e. 2x scaling these days.)