move rec su vars to system control page

[tyneises]

Both the Trough and Fresnel models included inputs on the Solar Field page for “Receiver startup delay time” and “receiver startup delay energy fraction”. These variables originated from the power tower model, where the component performance model uses these values to determine when the receiver can generate useful thermal energy. However, the trough and Fresnel performance model tracks the solar field temperature when the field is “off” (not sending heat to TES or cycle), so these two inputs are not used in the performance model. However, when trough and Fresnel is used in the dispatch model, we use these two inputs as a way for the dispatch model to guess the time and energy startup penalty for the field.

This pull request moves these two inputs from the Solar Field page to the System Control page for both trough and Fresnel.