The quality of life passive skills update

• Created overworld skills, it's now possible to change encounter rate and run faster thanks to these;
• Added new passive skill to revive Xander with full health once per battle;
• Switched placeholder buttons to an actual sprite;
• Update project to Unity 2020;
• Updated entire project to new Unity Input System, game should be fully compatible with controllers now;
• Reworked CharacterOW references to be stored inside their respective Character SOs;
• Created value change observers for SO float variables;
• Implemented input dependent images, that change image sprite based on last used control scheme;
• Fix to the build database function, some values were not being properly serialized;
• Import 2d extras as a package and update it to latest version;
• Add actions in repository to review code pushed to Develop using SonarCloud;