feat: add the possibility to account for TU lifetime in arbitrary units

Created by: guillaume-plc

• Add the possibility to account for TU lifetime in arbitrary units (meaning lifetime_mean_value and lifetime_standard_deviation units do not have to be years necessarily)

• The new table yearly_use_amount corresponds to the amount a TU is used in a given year, in the same units as those of lifetime_mean_value and lifetime_standard_deviation. Empty values are assumed to have lifetime data in years (i.e. default to a yearly use amount of 1 year/year)

Back-tested against the current version of dev for TUStock and TUFlow on France up to year 2000.