Add separate touch margin; use it on dock splitter and tab close (#1072)

* Fix portallist alignment handling so centering actually works

Now, alignment on PortalLists now only applies to the "cross-axis"
of each item, not the main axis.
So when you center a portallist itself, it won't add weird space
on the leading side of the list

* Fix text not drawing on top of a background, e.g., `<code>` tags

This worked in *most* but not all cases, e.g., if you had a ton of
inline code tags, some of them would rarely but deterministically
not show the actual text glyphs, but just an empty background.

* Avoid large margin on the left of `<code>` if it's on a new line

* Add a separate "touch" margin; use it on dock splitter and tab close

Without this, those dock UI elements are nearly impossible to grab
and press on a real touch screen device, even on my iPad.

Also, tweak cargo-makepad iOS and Android builds to use a polished
display name for the app (uppercase first character) by default.