[wasm][wasi] Allow to build wasi in library mode

[mkhamoyan]

By this PR we are supporting library mode for wasi.

Here are all possibilites to build wasi.

1. Create exe

   <Project Sdk="Microsoft.NET.Sdk">
     <PropertyGroup>
       <OutputType>Exe</OutputType>
       ...
     </PropertyGroup>
   </Project>
   

2. Use wasi specific C# api in standard library

   <Project Sdk="Microsoft.NET.Sdk">
     <PropertyGroup>
       <OutputType>Library</OutputType>
       <RuntimeIdentifier>wasi-wasm</RuntimeIdentifier>
       ...
     </PropertyGroup>
    </Project>
   

3. Create Wasm library

     <Project Sdk="Microsoft.NET.Sdk.WebAssembly">
       <PropertyGroup>
         <OutputType>Library</OutputType>
         <RuntimeIdentifier>wasi-wasm</RuntimeIdentifier>
         ...
       </PropertyGroup>
      </Project>
   

Fixes #96869

[ilonatommy]

Doesn't it fix #89577 as well?

[mkhamoyan]

Doesn't it fix #89577 as well?

No, these changes are for wasi.

[lewing]

Is this waiting for other changes or ready to go?

[mkhamoyan]

Is this waiting for other changes or ready to go?

@lewing It is ready to go unless there are further changes needed based on the review.

[maraf]

Looks good to me 👍

[mkhamoyan]

Failures are not related to PR changes.