Add Version method to NFT interface and implementation

Include `RunWithOutput` support in the command package and introduce version parsing logic, enabling retrieval of the nftables version and options.

version.go

@@ -0,0 +1,21 @@
+package nft
+
+type Version interface {
+	// Version returns the version of the nftables client.
+	Version() string
+	// Opts returns the options of the nftables client.
+	Opts() map[string]string
+}
+
+type version struct {
+	version string
+	opts    map[string]string
+}
+
+func (v version) Version() string {
+	return v.version
+}
+
+func (v version) Opts() map[string]string {
+	return v.opts
+}