Split [debian.sh] into multiple scripts inside a [debian] directory, adjusted references in other files to reflect changes

debian/sources.sh

@@ -0,0 +1,37 @@
+#!/bin/bash
+set -euo pipefail
+
+source \
+	/etc/os-release
+
+
+cat << EOF | tee /mnt/etc/apt/sources.list.d/${VERSION_CODENAME}.sources &> /dev/null
+# ${VERSION_CODENAME^}
+Enabled:		yes
+Types:			deb deb-src
+URIs:			http://deb.debian.org/debian/
+Suites:			${VERSION_CODENAME}
+Components:		main non-free-firmware contrib
+Signed-By:		/usr/share/keyrings/debian-archive-keyring.gpg
+
+# ${VERSION_CODENAME^} Security
+Enabled:		yes
+Types:			deb deb-src
+URIs:			http://deb.debian.org/debian-security/
+Suites:			${VERSION_CODENAME}-security
+Components:		main non-free-firmware contrib
+Signed-By:		/usr/share/keyrings/debian-archive-keyring.gpg
+
+# ${VERSION_CODENAME^} Updates
+Enabled:		yes
+Types:			deb deb-src
+URIs:			http://deb.debian.org/debian/
+Suites:			${VERSION_CODENAME}-updates
+Components:		main non-free-firmware contrib
+Signed-By:		/usr/share/keyrings/debian-archive-keyring.gpg
+EOF
+
+if [[ -f '/mnt/etc/apt/sources.list' ]]; then
+	rm \
+		/mnt/etc/apt/sources.list
+fi