Exim Advanced Editor - Add Management of dkim_sign_headers value

Hi

The current configuration of Exim Advanced Editor and exim.conf.local is limited to only the features or options that can be edited in Exim Advanced Editor.

Any other Exim control that needs to be edited, in my specific use case, dkim_sign_headers within the dkim_remote_smtp section, cannot be modified via Advanced Editor and consequently modifying exim.conf is not persistent and will need some level of daily management to ensure that Exim rebuild / restarts do not overwrite the manual edit.

Specifically, I need dkim_sign_headers to be an editable value. More generally I think there could be many other editable values catered for in the Exim Advanced Editor. Making each section of the exim.conf editable as a block which is stored within exim.conf.local as a persistent copy, or allowing manual edits of exim.conf.local would provide far more flexibility and remove the need for redundant manual processes to preserve customisations.

A thread regarding this exists at https://forums.cpanel.net/threads/selecting-header-fields-tags-for-dkim-signature.654487/

Further commentary consistent with this feature is found at https://forums.cpanel.net/threads/exim-taint-mismatch-string_nextinlist.689469/ where a similar issue cannot / could not be addressed without resorting to editing perl scripts that are overwritten with updates, and creating additional scripts and file copies in order to work-around the standardised Cpanel Exim configurations.