Add migrate command (#207)

* Add base and loader command

* Support updating to latest

* Support explicit fabric versions

* Support explicit Forge version

* Support quilt

* Add support for updating Minecraft

* Add support for Forge recommended

* Fix Forge version sorting

* Various fixes

* Add documentation to the use

* More suggestions

cmdshared/utils.go

@@ -0,0 +1,16 @@
+package cmdshared
+
+import "strings"
+
+func GetRawForgeVersion(version string) string {
+	var wantedVersion string
+	// Check if we have a "-" in the version
+	if strings.Contains(version, "-") {
+		// We have a mcVersion-loaderVersion format
+		// Strip the mcVersion
+		wantedVersion = strings.Split(version, "-")[1]
+	} else {
+		wantedVersion = version
+	}
+	return wantedVersion
+}