✨Use one-click approach for latest version numbers in welcome view

[BennyBot]

Requested Feature

Currently, the latest CLI version for welcome view is fetched by checking mainline’s upgrademanifest.json for latest release. This is annoying as we have to manually update upgrademanifest for every CLI update. This could be automated with some CI work, but the file currently is not useful besides the welcome view afaik.

Since we tag all releases, we can simply do what one-click does to find the latest versions. Get the latest release json from api.github and then just read the tag_name field.

An older method for kernel is also still present but unused in the code to use the cli to identify the latest kernel version, so this should be removed.

Benefits of Feature

Simpler code, we dont have to touch upgrademanifest again