Implemented Untrained Improvisation and Pathfinder Agent Dedication

Changes

1. Removed "hard coded" Untrained Improvisation code from character.ts
2. Added rule elements to the following feats:
   • Untrained Improvisation: adds flat proficiency modifier to all skill-checks equal to level/2 (level <7) or level (level >= 7)
   • Pathfinder Agent Dedication: adds flat proficiency modifier to all skill-checks equal to level
3. Removed reference to Untrained Dedication proficiency level from en.json

Notes/Issues

1. This no longer accounts for the Proficiency Without Level variant. Previously, if the game was set to Proficiency Without Level and the character had Untrained Improvisation, it would do nothing. In this change, both the Pathfinder Agent Dedication feat and the Untrained Improvisation feat will add level to the proficiency bonus. This could be an open issue, although it raises the question, "would a player choose Untrained Improvisation in a game with Proficiency Without Level?" As the GMG doesn't actually provide guidance, it's tough to say "what the right answer is."
2. Two of the pregen iconics (Feiya, level 5, and Quinn, level 5) have Untrained Improvisation and will likely have to be updated.