Support `org_do_promote` and `org_do_demote` in visual mode

Does this feature exist in Emacs orgmode core?

N/A

Orgmode link

No response

Feature value

I often need to promote and demote many elements at the same time, for example:

A group of headings:

* Heading 1
** SubHeading 1
** SubSubHeading 1 <-- heading to demote
** SubSubheding 2  <-- heading to demote

The content of a heading (following the case shown in https://github.com/nvim-orgmode/orgmode/issues/859)

* Heading 1
****** SubHeading 1
  - Line 1 <-- content to promote
    - Subline 2 <-- content to promote
  - Line 2 <-- content to promote

The natural way for me is to select all the content in visual mode and use >> or << but it falls back to the default nvim indentation change and adds the spaces:

* Heading 1
** SubHeading 1
  ** SubSubHeading 1 
  ** SubSubheding 2 

* Heading 1
****** SubHeading 1
	  - Line 1
	    - Subline 2
	  - Line 2

Additional context

No response

Start by tracing the existing org_do_promote and org_do_demote commands and how visual-mode mappings currently handle >> and <<. Reproduce the heading and content examples from the issue, then verify that visual selections use Orgmode promotion or demotion without adding ordinary indentation spaces.