Rework Find-SteamAppID to Get-SteamApp

[hjorslev]

Description

Resolves #79

• Adjust Update-SteamApp
  • so it is compatible with Get-SteamApp
  • rename parameter AppID to ApplicationID and add AppID as an alias
• Rework Find-SteamAppID to Get-SteamGame

Type of change

• [ ] 📖 [Docs]
• [ ] 🪲 [Fix]
• [ ] ⚠️ [Security fix]
• [ ] ♻️ [Refactor]
• [ ] 🎉 [Feature]
• [ ] ✨ Enhancement
• [x] 🌟 [Breaking change]

Checklist

• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have added Pester tests that covers the added cmdlets

[hjorslev]

It should write an error if the application couldn't be found.