[FR] Edit Conguration.h and Conguration_adv.h as single item.

[vovodroid]

As configuration is spitted between two files, it would be handy to have one common edit page for both of them.

[thinkyhead]

It should be possible to create a new custom Web View encompassing both configuration files, but we would lose the automatically provided document handling elements until they are re-implemented with file watchers and other tricks. At some point I will lock my doors, pull the shades, and try to build it out, but in the process I would not want to just throw away the VSCode "Custom Editors" implementation of it, and so we would then have two different solutions to accomplish the same thing.