fixes dotnet/templating#3038 show all available short names for template group

[vlada-shubina]

Problem

fixes #3038
fixes #2704

Solution

Templates can be matched by:

• any of short name they have
• any of short name the group have

However, in the table outputs (--list, --search) we only show first short name, and users are not aware about other names (se #3039).
This PR changes it - all short names now will be shown.

Checks:

• Added unit tests
• Added #nullable enable to all the modified files ?

[vlada-shubina]

Example of the output for ASP.NET now:

> dotnet new --list 
Template Name                                 Short Name     Language  Tags                  
--------------------------------------------  -------------  --------  ----------------------
Worker Service                                worker         [C#],F#   Common/Worker/Web     
Blazor Server App                             blazorserver   [C#]      Web/Blazor            
Blazor WebAssembly App                        blazorwasm     [C#]      Web/Blazor/WebAssembly
ASP.NET Core Empty                            web            [C#],F#   Web/Empty             
ASP.NET Core Web App (Model-View-Controller)  mvc            [C#],F#   Web/MVC               
ASP.NET Core Web App                          webapp,razor   [C#]      Web/MVC/Razor Pages   
Razor Class Library                           razorclasslib  [C#]      Web/Razor/Library     
ASP.NET Core Web API                          webapi         [C#],F#   Web/WebAPI            
ASP.NET Core gRPC Service                     grpc           [C#]      Web/gRPC              

[vlada-shubina]

I've opened dotnet/aspnetcore#33067 to remove multiple short names in ASP.NET Core Web App template and get their feedback on how their template is displayed after change.