When running the apt-check script. we are trying to get the distro
name and version from /etc/os-release. However, some distros do not
ship that file. If the system does not have that file or is missing
a required info there, we will now fallback to calling lsb_release.
When running apt-check on a esm distro, we display a header
showing the status of esm-infra on the system if we have esm-infra
source file on it. We should do the same for lts distros, but instead
of showing esm-infra status, we will show esm-apps status
If we have no package upgrades to apply to the system,
we would would not show the message stating that zero upgrades
can applied immediately to the system. We are now bringing that
message back for the zero upgrades scenario, since we found out
that it is hurting the user experience of the apt-check output.
For esm-infra alerts on ESM distros, we are now
updating the message to include the ubuntu version
of the machine running the script and also pointing
to a different url to see more information about esm-infra
Only show esm-apps alert on lts and non-esm distro
Currently, we are showing esm-apps alerts if the user
has an unauthenticated esm-apps source file and is using
a LTS distro. However, we don't want to show this alert if the
user is using a ESM distro, since esm-apps will not do much
in that situation. We are updating that alert to show only
if the user is not using a ESM distro.
