Explore compiler optimisation flags for each HPC system (`gadi` for now)

[manodeep]

There are a wide variety of compiler optimisation flags that could be applied to each component, and in combinations of the components (i.e., combinatorial choices). These flags need to be added during the compilation stage, and then the resulting code run and checked for i) successful run (i.e., no segfaults/errors) and ii) correctness - which is differently evalulated than bitwise identical results (as in, bitwise identical output is probably out the window when adding aggressive optimisation flags).

The benchmarking needs to be done in a systematic manner, and the associated simulation data + metadata needs to be kept around on the relevant HPC system (gadi for now). This work will probably need to be done in conjunction with scaling tests - that change how many cores/nodes are assigned to each component