Refactor DatabaseViewComponent

[oznogon]

• Use layout attributes to set padding on DatabaseScreen
• Use layout attributes to set margins between between item list Back button and list, and between columns
• Prevent extraneous bottom padding from being applied to item list
• Prevent database details column from overlapping with crew screen/ main screen controls

Also, this PR adds counting functions to PlayerInfo to support detecting when more than one crew screen is visible.

Before (first) and after

Database screen, no other crew screens:

Changes:

• Item list extends to the bottom of the screen, responsive to view height
• Details column extends to the top of the screen
• Padding tightened on either side of the key-value column
• Crosses pattern applied to background

Science screen, with other crew screens and main screen controls selected:

Changes:

• Item list extends to 20px above the top of the view control buttons, responsive to view height
• Details column starts 20px below the bottom of the main screen controls button