[Task]: remove composer archives from examples

[norberttech]

What needs to be done?

Since we can now run examples in playground, we can remove building/archiving composer archives in the examples.

We can also get rid off:

• handling/displaying output
• executing examples
• creating downloadable archive
• installing dependencies

Instead each example should be rendered with it's own playground.
This means we need to move examples from /examples into web/landing/templates/playground/examples

That should also significantly improve rendering examples on the website.

We should create a generic web/landing/templates/playground/examples/example.html.twig which all examples are going to extend by passing whatever is custom for them, like:

• predefined datasets
• input data
• etc

Then instead of having web/landing/src/Flow/Website/Service/Examples.php that scans the /examples directory we can make each example just a static page with a static route (that will be a bit of manual work)

We should also adjust examples to writ(to_output()) instead of writing to file