* feat(go/backtracking): add go code
* feat(backtracking): add n_queens in go
* feat(backtracking): add /preorder_traversal_i_compact in go
* feat(backtracking): add /preorder_traversal_ii_compact in go
* feat(backtracking): add /preorder_traversal_ii_template in go
* feat(backtracking): add preorder_traversal_iii_compact in go
* feat(backtracking): add preorder_traversal_test in go
* feat(backtracking): add permutations_i in go
* feat(backtracking): add permutations_ii in go
* feat(backtracking): add permutation_test in go
* feat(backtracking): fix bug in go
* Update permutations_i.go
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Co-authored-by: Yudong Jin <krahets@163.com>
