Default values for variables are not used when starting the server through code

[joachimvh]

Description

https://github.com/CommunitySolidServer/CommunitySolidServer/pull/1100 states the following:

Default values have been removed from the CLI options and moved to the ValueComputers

This might be controversial. This is also related to the run option. By moving the defaults to the computers, users that use the run function also can make use of these defaults. There is currently an issue with the current version of AppRunner where the run function can only be used if the user explicitly provides a value for the showStackTrace parameter, even though the CLI parameter defaults to false. This resolves such issues.

This is actually not true. Currently the AppRunner immediately creates an App when calling run/create without calling any of the variable logic. This should be changed so they are used as that was the original intent.