Add support for Yazi-FM's 'ya' package manager

[OnyxAbove]

I want to suggest a new step

• Which tool is this about? Where is its repository?

This is about the 'ya' package manager for the Yazi TUI file manager. I'm not sure if there is a separate repo for 'ya' but the one for Yazi is at https://github.com/sxyazi/yazi

• Which operating systems are supported by this tool?

Windows, MacOS, And linux are all supported

• What should Topgrade do to figure out if the tool needs to be invoked?

Run ya in the terminal.

• Which exact commands should Topgrade run?

ya pack -u

• Does it have a --dry-run option? i.e., print what should be done and exit

No, it doesn't.

• Does it need the user to confirm the execution? And does it provide a --yes
  option to skip this step?

This is the default behavior.