Merges tutor code back into the rascal project

[jurgenvinju]

• used git-filter-repo to remove all unnecessary scaffolding from rascal-tutor, and rename its source folder to
  src/org/rascalmpl/tutor.

# cloned rascal-tutor from scratch
git clone [email protected]:usethesource/rascal-tutor.git
# this removed everthing from the project's history except this path:
git-filter-repo --path src/lang/rascal/tutor  
# this put the code back into the original folder in the rascal project (src/org/rascalmpl/tutor)
git-filter-repo --path src/lang/rascal/tutor --path-rename src/lang/rascal/tutor:/src/org/rascalmpl/tutor/lang/rascal/tutor 
# remove all the tags locally
git tag --delete $(git tag --list)
# remove all the branches locally (except the main branch and possibly a current branch marked with *)
git branch remove $(git branch --list | grep -v "^\*" | grep -v "main")
# then switch to the rascal project
cd ../rascal
git checkout -b adopt-tutor
# add the clean project as a remote
git remote add -f tutor-baby ../rascal-tutor
# merge the code into this branch
git merge tutor-baby/main --no-ff --allow-unrelated-histories

The goal is to:

• move the selenium dependent code to rascal-maven-plugin as a service
• load this service via dependency injection into the tutor repl executor
• make sure the tutor's tests are executed by the rascal project as well
• make sure the rascal-maven-plugin can work without a dependency on the old rascal-tutor project
• remove the rascal-tutor from the website
• make sure the rascal-tutor documentation is added to the Rascal documentation

[jurgenvinju]

See usethesource/rascal-maven-plugin#22 for the use of these changes in the rascal-maven-plugin project, which now depends on selenium to make the screenshots.

[jurgenvinju]

See usethesource/rascal-website#58 for the addition of the tutor's documentation to the website.