infra: separate update script

[07CalC]

proposal

Currently we deliver ota updates with the same installation script used while installation, it works but not a great practice.

• fix the update.sh to work properly as it should
• bundle the update mechanism with mist-cli

[07CalC]

Changing the update flow will also be beneficial.

Clone the latest release via go binary only, then execute the update.sh, this will ensure we can iterate update.sh in single update rather than 2 different.