[PLAT-6734] Corrected call to volatility for options on STIR futures.

A similar bug appeared several time in the code: rateStrike was used instead of PriceFuture for the volatility interpolation. Corrected several times.
Change some formatting to fit the 120 char.
Change the unit tests to make sure that the strike is in the interpolation zone (not the extrapolator zone).

@traggattog Can you review this?