lang/nim: Update to 1.2.0

• Remove files/patch-koch.nim (This patch is not needed to build nim and tools)
• Update files/patch-install.sh and files/patch-config-nim.cfg
• Unbreak arm (fixed upstream) [1]
• Add all optional tools
• Order pkg-plist
• Move USES (pet portlint)

[1] https://github.com/nim-lang/Nim/pull/13822

Changelog:

• https://nim-lang.org/blog/2020/04/03/version-120-released.html

PR: 245328
Approved by: tcberner (mentor), Neal Nelson (maintainer)
Differential Revision: https://reviews.freebsd.org/D24294