[FEATURE]Add "closed" column in org-ql dynamic blocks

Dynamic blocks are great, could we add clsoed as table column argument to specify TODO closed time

Example:
```
#+BEGIN: org-ql :query "todo: priority:A,B" :columns (todo (priority "P") deadline heading closed) :sort (deadline priority) :take 7 :ts-format "%Y-%m-%d :file org-agenda-files"
| Todo | P | Deadline | Heading | Closed |
|------+---+------------------+---------------------------------------|---------|
| TODO | A | 2017-07-07| Take over the world |2021-09-01|
#+END:
```
I tried to use `(property closed)` but it was not a string, so not work

[relate code:org-ql-search.el#L300 ](https://github.com/alphapapa/org-ql/blob/94f9e6f3031b32cf5e2149beca7074807235dcb0/org-ql-search.el#L300)
```elisp
(cons 'property (lambda (element property)
(org-element-property (intern (concat ":" (upcase property))) element))
```
I am not familiar with ELISP and am not sure if I have found the correct code location