Item templates should pick correct language from project

### Is your feature request related to a problem? Please describe.

When using a item template inside a F# project, e.g.
`dotnet new avalonia.templatedcontrol`
I would expect that the option `-lang=F#` would not be required but it is.
So it is using the C# version by default when the `-lang=F#` was omitted/forgotten.

### Describe the solution you'd like.

The solution should be that the templating engine should detect that the item template is added to a project of a known language, when the item template has multiple matching identities with different `lang` tags the correct one should be picked.

### Additional context

Somewhat related to: #5358

Also I am aware of #2684 but I don't think that is a solution when e.g. you mostly use C# but only sometimes F#.