Add an icon and title to generic widget containers

[naschmitz]

Overview:

• Add an icon and title to the generic widget container.
• Close and minimize buttons moved to the right-hand side of the widget container.
• Title HTML element expands to fill the gap in the header.
• Fixed other small bugs discovered while updating the unit tests.
• Other widgets that use the generic container should set title and icon on the container.

TODOs:

• Basemap selector (once submitted and rebased).

Screenshots:

[sufyanAbbasi]

Solid, thank you!