Problem
This ticket is used for command implementation
cortex should be able to update itself
Proposed command: eg for v0.5.0-120

cortex update -v <version>

cortex update

If version is not specified then pull the latest version

Additional context
UX for cortex update is discussed in: #1041

Features / Tasklist

• Updater for stable release
• ci: Updater for beta release #1169
• ci: Updater for nightly release #1170

Bugs

• bug: check new update hang if network is down #1350
• bug: cortex update stdouts "Update cortex sucessfully" even when update failed #1257
• bug: running cortex update on latest version should gracefully inform "already up to date" #1278
• bug(flaky): Download progress counter fails to self update #1307
• bug: cortex update fails, filesystem error: Text File busy (Linux) #1311