Add Hephaestus.Installer

[CreepPork]

Hephaestus.Installer is to be implemented in C++ or Rust.

• Add checking for .NET Core
• Add checking for .NET Framework (if on Windows)
• Install .NET Core (or redirect the user to the page where to download the required .NET Core verison)
• Install .NET Framework (if on Windows)
• Install Hephaestus from GitHub releases
• Register Hephaestus command in the alias in Bash (if used)

[CreepPork]

Probably going to be written in a different language from C#, as it should be implemented without any other dependencies so it can install or point the user to the required dependencies.