test: Add tests for resolved issues

[lukemanley]

Tests added in this PR for open issues that are already fixed:

closes #4175
closes #12775
closes #13117
closes #14651
closes #17327

Other open issues that have already been resolved (just noting tests in order to close):

closes #7683 - test_split_expr.py::test_split_expr
closes #9718 - test_array.py::test_arr_first_last, test_array.py::test_array_get
closes #10137 - test_join.py::test_join_numeric_type_upcast_15338
closes #11853 - test_lazy_parquet.py::test_parquet_schema_arg
closes #11917 - test_explain.py::test_lf_explain_format_tree
closes #13846 - test_concat_arr.py::test_concat_arr
closes #14540 - test_concat_arr.py::test_concat_arr
closes #17514 - test_is_in.py
closes #18018 - test_enum.py::test_init_from_enums
closes #18419 - test_window.py::test_window_order_by_8662