Arlon CLI new version check

[cre8minus1]

The Arlon CLI needs to check for new versions and notify users to upgrade.
This could also be automatic, however this will require all changes to not be breaking changes.

At a minimum users should be able to run arlon version and see their current version

• Upgrade to be handled separately with arlon update to upgrade. Arlon CLI self-update #254
  The version command should return the current version and if a new version is available.

Aha! Link: https://pf9.aha.io/features/ARLON-155

[Rohitrajak1807]

This could also be automatic, however this will require all changes to not be breaking changes.

This requirement will need some thought.

[cruizen]

Deferring to sprint 9

[cruizen]

If a user is on v0.3.5, the output of arlon version will be like : Arlon v0.3.5 \n Arlon is outdated. A new version v0.3.7 is available. Please update Arlon ....
If a user is on v0.9.1, the output of arlon version will be like : Arlon v0.9.1 \n Arlon is outdated. A new version v0.9.12 is available. Please update Arlon ....

We will need to maintain the latest update version for each Arlon minor version.
arlon update can in future ask the user if they want to update to a new major version - and warn if required if that's a breaking change.

For the solution: We can maintain the latest available version for a release in a public location like GitHub release artifacts list.