CI: Run Exercises pipeline produces output for all exercises

[mrzzy]

Motivation

Run Exercises pipeline produces output for all exercises SQL:

• This makes it hard to locate the output for the exercise SQL file that we actually are working on and have changed.
• Users have to search for the file header to file the relevant output.

Requirements

Must Haves:

• Run exercises output should be limited by exercise, allowing users to quickly narrow down on the output they are looking for.

Good to have:

• Separate workflow files each and every exercise, this gives us nice workflow badges for each workflow:

Proposal

• Create new GIthub Actions workflow / job that only runs the exercises files that have changed
  • use github.event to determine which exercise files have changed.