Boolean defaults and artwork displays

[nathanacurtis]

Problem

When spec'ing boolean properties, the plugin isn't resulting the artwork expected:

1. When the selected variant doesn't include layer(s) associated with the boolean property, the artwork and content lacks the annotation of the associated layers.
2. When multiple boolean properties are interdependent, the plugin may reveal both, resulting in a unexpected / unfeasible display.

[nathanacurtis]

Relevant Slack discussion
https://eightshapes-specs.slack.com/archives/C059J8DGDM5/p1724846236877449