rescale_skills: Rescale O-NET skills
In djmorris1989/onetmappinguk: Map US O-NET to the UK SOC-2010

This function adjusts the skills data. Some skills were valued by job incumbents, others by occupational experts/analysts. As job incumbents are likely to systematically over-value skill level/importance, the raw skill measures in O-NET are adjusted to account for this. Each skill level and importance measure is regressed on occupation fixed effects, year fixed effects, and a dummy variable indicating if the occupation was rate by job incumbents. The value of this coefficient is subtracted from the skill measure reported by job incumbents.