gnu: icedove: Update to 78.3.0.

gnu: icedove: Update to 78.3.0.

* gnu/packages/gnuzilla.scm (icedove): Update to 78.3.0.
[source]: Use source from Icecat 78.
[arguments]: Use more flexible approach for generating cargo checksums
from icecat. Update files in 'rename-to-icedove phase. Remove gone
configure flags and rename `--disable-ion` to `--disable-jit`.
[inputs]: Update icu4c to version 67 and nss to 3.56.
[native-inputs]: Use ESR 78 mercurial repo for thunderbird soruces.
Update rust and cargo to 1.41, rust-cbindgen to 0.14 and
node to 10.22.

Tested-by: Jonathan Brielmaier <jonathan.brielmaier@web.de>
Signed-off-by: Mark H Weaver <mhw@netris.org>