UPDATE operations don't allow updating subscripted array values

The `:at` operator lets us index into arrays in SQL: ```clojure (honey.sql/format {:select [[[:at :my-array 14]]]}) => ["SELECT my_array[14]"] (honey.sql/format {:select [[[:at :my-array {:select :value :from :some-cte}]]]}) => ["SELECT my_array[(SELECT value FROM some_cte)]"] ``` It should be possible to use the same syntax in UPDATE statements. [From the postgres docs](https://www.postgresql.org/docs/current/arrays.html#ARRAYS-MODIFYING): ```sql UPDATE sal_emp SET pay_by_quarter[4] = 15000 WHERE name = 'Bill'; -- or updated in a slice: UPDATE sal_emp SET pay_by_quarter[1:2] = '{27000,27000}' WHERE name = 'Carol'; ``` However this can't be formatted in honeysql: ```clojure (honey.sql/format {:update :tbl :set {[:at :my-array 14] 99}}) Execution error (ExceptionInfo) at honey.sql/name (sql.cljc:257). expected symbol, found: class clojure.lang.PersistentVector ```