Prevent loss of Advantage when becoming Engaged

Adds compatibility with Engaged pseudo-condition, so that when a character gains the Engaged condition, they do not lose their Advantage.

Type of change

[x] I have run linting on my code to follow the follow the style of this project.
[x] My changes generate no new unhandled or unexpected warnings.
[x] My change requires an update to the documentation.

Fixes or addresses #issue(s): #206

Token actors would incorrectly lose Advantage when gaining the Engaged condition, introduced in WFRP4e 6.2.0.

Replace condition check with more easily extensible nonCondition array to check inclusion against.
Check for unlinked and non-PC tokens as well as actors to prevent condition check failing, which would also prevent Advantage from being cleared.