`dotnet new global.json --sdk-version` incorrectly accepts invalid SDK versions like `9.0.x`, emit error instead

[Frulfump]

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

Since dotnet/runtime#118418 adds a warning in dotnet --info for invalid version strings in .NET 10, let's stop one vector where you can add an invalid version string since not everyone will run dotnet --info.

The invalid version formats:
9 i.e ^\d+$
9.0 i.e ^\d+.\d+$
9.0.0 i.e ^\d+.\d+.\d+$
9.0.x i.e ^\d+.\d+.[xX]$

and only allow the format 9.0.100 i.e ^\d+.\d+.(?:[1-9]\d{2})$

(Note: \d allows non 0-9 digits i.e digits from other "languages" so would be better to be explicit and only allow the range 0-9)

Describe the solution you'd like

Ideally error on invalid version strings, maybe provide a way to force it.

Additional context

Ref: #49816
Ref: dotnet/runtime#118418 adding a warning for dotnet --info

[baronfel]

This is blocked on implementing something like dotnet/templating#2038 in the template engine itself - most kinds of symbols do not have any validation aside from

• data-type validity
• valid choice values
• required or not