feat: Improve code quality by minimizing nested code (e.g. if/else conditional blocks)

[Gitsarry]

I confirm this feature has not been previously requested

• I have searched the issues and this feature has not previously been requested

Example of current nested code

function ignore_msrs_always() {
    # Make sure the host has /etc/modprobe.d
    if [ -d /etc/modprobe.d ]; then
        # Skip if ignore_msrs is already enabled, assumes initramfs has been rebuilt
        if grep -lq 'ignore_msrs=Y' /etc/modprobe.d/kvm-quickemu.conf >/dev/null 2>&1; then
            echo "options kvm ignore_msrs=Y" | sudo tee /etc/modprobe.d/kvm-quickemu.conf
            sudo update-initramfs -k all -u
        fi
    else
        echo "ERROR! /etc/modprobe.d was not found, I don't know how to configure this system."
        exit 1
    fi
}

Describe the solution you'd like: Exit early, so no else clause needed, code gets simpler and more easy to read

function ignore_msrs_always() {
    # Make sure the host has /etc/modprobe.d
    if [ ! -d /etc/modprobe.d ]; then
        echo "ERROR! /etc/modprobe.d was not found, I don't know how to configure this system."
        exit 1
    fi

    # Skip if ignore_msrs is already enabled, assumes initramfs has been rebuilt
    grep -lq 'ignore_msrs=Y' /etc/modprobe.d/kvm-quickemu.conf >/dev/null 2>&1 && return

    # if all conditions met, write file
    echo "options kvm ignore_msrs=Y" | sudo tee /etc/modprobe.d/kvm-quickemu.conf
    sudo update-initramfs -k all -u
}

See e.g. Computer Programming/Coding Style/Minimize nesting “Flat is better than nested”