Refactor entity options to use shared base class

Introduce EntityBaseOptions with Columns property.
Update EntityOptions and VirtualEntityOptions to inherit from EntityBaseOptions for improved code reuse and consistency.

src/ReC.Infrastructure/Options/Shared/EntityBaseOptions.cs

@@ -0,0 +1,6 @@
+namespace ReC.Infrastructure.Options.Shared;
+
+public record EntityBaseOptions()
+{
+    public Dictionary<string, string> Columns { get; init; } = [];
+}

src/ReC.Infrastructure/Options/Shared/EntityOptions.cs

@@ -1,3 +1,3 @@
 namespace ReC.Infrastructure.Options.Shared;
 
-public record EntityOptions(TableOptions Table);
+public record EntityOptions(TableOptions Table) : EntityBaseOptions;

src/ReC.Infrastructure/Options/Shared/VirtualEntityOptions.cs

@@ -1,3 +1,3 @@
 namespace ReC.Infrastructure.Options.Shared;
 
-public record VirtualEntityOptions;
+public record VirtualEntityOptions : EntityBaseOptions;