Port go package to universe to resolves #1553

Definition are now split in their own file.
`#Image` is a simple base image to set up a go container
`#Container` is a standalone environment to execute go command, any go command
should use this definition.
It shares `docker.#Run` fields to easily maintains this definition.
`#Build` and `#Test` are high level definition that use `#Container` to
execute common go operation in a CI.

Those definitions are tested with a simple greeting package.

Signed-off-by: Vasek - Tom C <tom.chauveau@epitech.eu>

pkg/universe.dagger.io/go/build.cue

@@ -0,0 +1,51 @@
+package go
+
+import (
+	"dagger.io/dagger"
+	"dagger.io/dagger/engine"
+)
+
+// Build a go binary
+#Build: {
+	// Go version to use
+	version: *#Image.version | string
+
+	// Source code
+	source: dagger.#FS
+
+	// Target package to build
+	package: *"." | string
+
+	// Target architecture
+	arch: *"amd64" | string
+
+	// Target OS
+	os: *"linux" | string
+
+	// Build tags to use for building
+	tags: *"" | string
+
+	// LDFLAGS to use for linking
+	ldflags: *"" | string
+
+	// Target binary output
+	output: string
+
+	env: [string]: string
+
+	_build: #Container & {
+		"version": version
+		"source":  source
+		"env":     env
+		args: ["build", "-v", "-tags", tags, "-ldflags", ldflags, "-o", output, package]
+	}
+
+	_copy: engine.#Copy & {
+		input:    engine.#Scratch
+		contents: _build.output.rootfs
+		source:   output
+		dest:     output
+	}
+
+	binary: _copy.output
+}