Single magical bootargs

[Itxaka]

What this PR does / why we need it:

Merge all bootargs from all flavors into a single bootargs that can infer the actual flavor and set the proper cmdline for each one.

The idea is to merge this, test this and then move the bootargs into the package with the yip configs and such so its installed on the framework directly and shipped as the default bootargs thus removing it from here.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

[Itxaka]

ubuntu:

kairos@localhost:~$ cat /proc/cmdline 
BOOT_IMAGE=(loop0)/boot/vmlinuz console=tty1 net.ifnames=1 rd.cos.oemlabel=COS_OEM rd.cos.oemtimeout=10 panic=5 rd.emergency=reboot rd.shell=0 systemd.crash_reboot=yes root=LABEL=COS_ACTIVE cos-img/filename=/cOS/active.img security=selinux selinux=1 console=ttyS0 rd.emergency=reboot rd.shell=0 panic=5 systemd.crash_reboot systemd.crash_shell=0
kairos@localhost:~$ cat /etc/os-release 
PRETTY_NAME="Ubuntu 23.04"
NAME="Ubuntu"
VERSION_ID="23.04"
VERSION="23.04 (Lunar Lobster)"
VERSION_CODENAME=lunar
ID=ubuntu
ID_LIKE=debian
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
UBUNTU_CODENAME=lunar
LOGO=ubuntu-logo
KAIROS_NAME="kairos-core-ubuntu"
KAIROS_VERSION="v2.4.0-5-gd252ef2"
KAIROS_ID="kairos"
KAIROS_ID_LIKE="kairos-core-ubuntu"
KAIROS_VERSION_ID="v2.4.0-5-gd252ef2"
KAIROS_PRETTY_NAME="kairos-core-ubuntu v2.4.0-5-gd252ef2"
KAIROS_BUG_REPORT_URL="https://github.com/kairos-io/kairos/issues"
KAIROS_HOME_URL="https://github.com/kairos-io/kairos"
KAIROS_IMAGE_REPO="quay.io/kairos/core-ubuntu"
KAIROS_IMAGE_LABEL=""
KAIROS_GITHUB_REPO="kairos-io/kairos"
KAIROS_VARIANT="core"
KAIROS_FLAVOR="ubuntu"

[mudler]

given the large amount of logical changes in the grub configuration probably this should have been going into a 2.x branch rather than a patch release