Support dark theme in ESCET

We are addressing text editor dark theme support in #347 (closed), but this is not all that needs to happen. We discussed some things in this discussion: !331 (comment 828288).

Some things that I noticed are not dark theme compatible yet:

• (!374 (merged)) Our console uses hard coded black foreground text for stdout.
• (!374 (merged)) The applications view legend background doesn't look good.
• (!374 (merged)) (!385 (merged)) The CIF plot visualizer has hardcoded colors for a light theme.
• The SVG viewer (for opening .svg files) and visualizers (for the Chi and CIF simulators) use a hardcoded white background color.
  • I opted not to change the background for SVG images (SVG viewer, Chi/CIF simulator visualizers), as current images are probably made for a white background, and changing the background color would lead to unreadable SVG images.
• (!374 (merged)) The Checkstyle warning color is yellow, and does not play well with a dark theme development environment. Though this is not directly ESCET product related, nor affecting end users.
• (!385 (merged)) The CIF simulator interactive GUI input component has various hardcoded colors.
• (!383 (merged)) The CIF event-based synthesis analysis tool has some hardcoded colors.