feat: support .NET

Signed-off-by: Olli Janatuinen <olli.janatuinen@gmail.com>

pkg/universe.dagger.io/x/olli.janatuinen@gmail.com/dotnet/test/image.cue

@@ -0,0 +1,39 @@
+package dotnet
+
+import (
+	"dagger.io/dagger"
+	"universe.dagger.io/x/olli.janatuinen@gmail.com/dotnet"
+	"universe.dagger.io/docker"
+)
+
+dagger.#Plan & {
+	actions: test: {
+		_source: dagger.#Scratch & {}
+
+		simple: {
+			_image: dotnet.#Image & {}
+
+			verify: docker.#Run & {
+				input: _image.output
+				command: {
+					name: "/bin/sh"
+					args: ["-c", "dotnet --list-sdks | grep '6.0'"]
+				}
+			}
+		}
+
+		custom: {
+			_image: dotnet.#Image & {
+				version: "5.0"
+			}
+
+			verify: docker.#Run & {
+				input: _image.output
+				command: {
+					name: "/bin/sh"
+					args: ["-c", "dotnet --list-sdks | grep '5.0'"]
+				}
+			}
+		}
+	}
+}