Add 'no economic assumptions' policy reform

[nikhilwoodruff]

This should turn off all growthfactor uprating, so we can identify the effects of economic assumptions in outputs.

[MaxGhenis]

Even to the current year, or just flat projections?

[janton10]

This should turn off all growthfactor uprating, so we can identify the effects of economic assumptions in outputs.

I'm not confident this will be insightful. Worth testing with one plot before implementing.

[janton10]

E.g. Turning off CPI uprating (i.e. 0% inflation) is itself an economic assumption.