feat(Ship Map): Add deck creation and image upload.

[alexanderson1993]

Description

Makes it possible to create new ship decks, reorder ship decks, and upload and remove ship deck images. Includes a pan-zoom view for the ship deck images too.

Related Issue

Closes #166.
Closes #171.

How do you know the changes work correctly?

Manual test

• Go to the ship plugin config
• Go to the "Ship Map" option
• Create a deck
• Create another deck
• Reorder the decks by dragging between the decks
• Upload an SVG image to one of the decks
• Pan and zoom in the view.

Screenshots (if appropriate):

Types of changes

• Docs Change (changes were only made to documentation)
• Refactor (non-breaking change which improves code)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to
  change)

Checklist:

• I have read the CONTRIBUTING document.
• My code follows the code style of this project.
• My change requires a change to the built-in project documentation.
• My change adds dependencies to this project.
• I have added tests to cover my changes.
• All new and existing tests passed.