Include Goblint-Http Server in GobView repository

[stilscher]

Because the Http-Server is an interface to Goblint in server mode that is solely used for GobView, we thought about integrating it into this repository. This should simplify the setup for GobView and the build steps that are necessary when developing.

The PR contains the following changes:

• include relevant files from the goblint-http-repository in a sub-directory in the gobview repository
• allow to build the http-server executable together with GobView
• extend the http-server to execute an initial Goblint run that writes out all files necessary for the web page (previously running goblint once separately with the gobview option enabled was required to run GobView)
• use the http-server to serve the files also (instead of running a separate python http server for serving the files)

The associated changes that were necessary in the analyzer repository are included in this PR: goblint/analyzer#1060

[sim642]

I force pushed to this branch to replace the manual copying of files from the other repository with a git merge to preserve all the git history for goblint-http-server.