For optaplanner-quickstarts

• remove license headers (Quarkus does it)
• [V] remove trim() (Less is more)
• [V] Quarkus getting started doc: gradle build explanation too (like Spring one)
• Extract common js for Tango color and showErrorDialog
• [V] Replace style="margin-bottom: 5px" with class="mb-2"
• 'show' => "show"
• [V] class="card lesson" but that lesson class is dead code
• Standarize use of js-joda over momentjs etc.

Big issues might be pulled into their own jira's.