PostgreSQL support and toolbar icon update

• #18 Fix toolbar dice icon
• #7 Generate values, increase maximum columns
• Generate values, PostgreSQL support
• Various updates and bug fixes

Dark mode support, various bugfixes

• Fluent UI dark mode icons
• Extra SQL options
• Various bugfixes

Improved usability and bugfixes

• Generate Values more user-friendly
• Code clean-up
• Various bugfixes