Strong api string localizers generator using incremental generator

[jirikanda]

• No longer generates marker classes (no garbage in IntelliSense 💪).
• No longer uses DelegatingStringLocalizer (Havit.Extensions.Localization now has no purpose).
• Generates neutral value comments in the code.
• No longer searches for or uses the ResourceServiceCollectionInstaller partial class (the generator now produces its own static class).
• Includes a unit test.

• Localizers no longer implement IStringLocalizer<>, they implement only IStringLocalizer (therefore, no marker class is needed).
• Generators cannot detect RESX files unless explicitly mentioned in the .csproj file.
• Generates a warning when no RESX file is found, including a hint on how to modify the .csproj file (can check if this can be implemented using a code fix).
• Uses a clone of HttpUtilityExt for human-readable, culture-specific character HTML encoding (e.g., "á" remains "á" and is not converted to an HTML entity).

• Does not depend on the latest version of Microsoft.CodeAnalysis.* (not 4.12.0, but 4.8.0). The reason is to be able to well used with other nugets. Ie. Microsoft.EntityFrameworkCore.Design depends on Microsoft.CodeAnalysis.Workspaces.MSBuild and Microsoft.CodeAnalysis.CSharp.Workspaces 4.8.0+. BUT these libraries have other dependecies on a single version (check ie on Microsoft.CodeAnalysis.CSharp.Workspaces. So if we use latest version, user of our library, who also uses EF Core, must manually specify version of Microsoft.CodeAnalysis.Common, Microsoft.CodeAnalysis.CSharp.Workspaces, Microsoft.CodeAnalysis.CSharp.Workspaces.Common and Microsoft.CodeAnalysis.Workspaces.MSBuild to the latest version.

[hakenr]

lgtm, waiting for the <AdditionalFiles Include="**\*.resx" /> investigation

[hakenr]

lgtm