.NET C# no way to enable different .NET sdk's on .netcore projects!

[lolrobbe2]

What does this PR do?

Add support for setting .NET sdk using dotnetsdk option. (only on new format projects otherwise just use the defautl)

Web Razor Worker Blazor (BlazorWebAssembly) WindowsDesktop default (Microsoft.NET.Sdk)

How does this PR change Premake's behavior?

adds a new option called dotnetsdk

Anything else we should know?

Add any other context about your changes here.

Did you check all the boxes?

• [x] Focus on a single fix or feature; remove any unrelated formatting or code changes
• [x] Add unit tests showing fix or feature works; all tests pass
• [x] Mention any related issues (put closes #XXXX in comment to auto-close issue when PR is merged)
• [x] Follow our coding conventions
• [ ] Minimize the number of commits
• [x] Align documentation to your changes

You can now support Premake on our OpenCollective. Your contributions help us spend more time responding to requests like these!

for some reason it took the commits from my previous pr (add C# documentation file to) i didn't change these files tho!

closes #2288