Fixing bug in Hovmoller_Temperature_Depth (#466)

* Converting Hovmoller_Temperature_Depth to use intake catalogue

* Altering Hovmoller_Temperture_Depth to fix bug in cell area with depth

* altering Hovmoller_Temperature_Depth to do spinup relative to year 1 (as this is what this script is usually used for)

* minor tweaks

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Co-authored-by: Navid C. Constantinou <[email protected]>