WIP: libunistring: update to 1.4.1

[NyaaaWhatsUpDoc]

• splits bootstrappable binutils into a separate chroot-binutils that doesn't rely on debuginfod (which pulls in curl, and so libidn2 / libpsl, which causes a dependency cycle on libunistring update)
• removes curl as a possible dependency of chroot-git to avoid potentially pulling in a curl dependency (see above)
• updates libunistring to latest

given i'm not quite so seasoned a contributor here, if anyone would prefer someone else take maintainer role of chroot-binutils by all means go ahead.

i'm also totally open to less destructive alternatives to manage this dependency cycle in trying to update libunistring! though it does seem like a similar situation to this could come about in the future with other dependencies, given our bootstrappable packages can potentially pull in non-bootstrap dependencies during binary-bootstrap.

binary-bootstrap works as expected, currently testing a full bootstrap now.

cc: @Duncaen (these were the changes i was asking about in IRC last week)
cc: @Gottox

[NyaaaWhatsUpDoc]

the failing runners are actually a good example of what happens if you try this PR without rebootstrapping 😅