Parent search bug fix

[adamsitnik]

Every symbol can have multiple parents. When getting the completions for commands, the global options defined by the parent commands should be included as well. The problem was that we were searching only the parents of current command (flat, one level above), rather going up in the hierarchy to reach the root command

Discovered by dotnet/sdk#29131

[KalleOlaviNiemitalo]

This seems wrong to me. Instead of looking at statically defined ancestry of the Command, it should get the CommandResult objects from the ParseResult in order to know which intermediate commands were actually used.

I.e. if you have

• RootCommand: subcommands { Mid1Command, Mid2Command }
• Mid1Command: subcommands { LeafCommand }, options { GlobalOption1 }
• Mid2Command: subcommands { LeafCommand }, options { GlobalOption2 }

and the user is asking for completions of "Mid2 Leaf", then it should offer only GlobalOption2 and not GlobalOption1.

[adamsitnik]

@KalleOlaviNiemitalo thank you for excellent feedback! I've added a failing test based on it and provided the fix. PTAL again