Welcome screen data entry improvments, and API mem saftey

[lissy93]

Several reliability and usability improvments

• Hides user input for pass while typing for interactive setup
  • Fixes Do not print password when typing it in #57
• Adds a lot of data struct safeguards for unexpected api responses
  • Should fix Latest version of AdGuard has changed API response, AdGuardian-Term needs to update schemas #26
  • Should also fix actual version #29
• Updates paths in the quick-start.sh install script
  • Fixes Bug on quick-start.sh files.  #31
• Adds upto 3 retries for initial network request during setup
• Adds request timeout to prevent hanging (default 5 sec, configurable with ADGUARD_TIMEOUT)