refactor(odin): Migrated nushell-completion command to go.

cmd_nushell_completion_test.odin

@@ -0,0 +1,36 @@
+package main
+
+import "core:fmt"
+import "core:strings"
+import "core:testing"
+
+@(test)
+test_nushell_completion_nonempty :: proc(t: ^testing.T) {
+	testing.expect(t, len(COMPLETION_SCRIPT) > 0, "completion script should not be empty")
+}
+
+@(test)
+test_nushell_completion_contains_externs :: proc(t: ^testing.T) {
+	expected := []string{
+		"tracked-paths",
+		"untracked-paths",
+		"envr backup",
+		"envr check",
+		"envr edit-config",
+		"envr help",
+		"envr init",
+		"envr list",
+		"envr remove",
+		"envr restore",
+		"envr scan",
+		"envr sync",
+		"envr nushell-completion",
+	}
+	for ext in expected {
+		testing.expect(
+			t,
+			strings.contains(COMPLETION_SCRIPT, ext),
+			fmt.tprintf("expected script to contain %q", ext),
+		)
+	}
+}