Whisk: Move non-preset values to config

[dapplion]

Preset values should be those that affect types or other build time data structures.

Both WHISK_EPOCHS_PER_SHUFFLING_PHASE and WHISK_PROPOSER_SELECTION_GAP do not affect any data structure and are useful to tweak in tests to speed up their runtime. Setting WHISK_PROPOSER_SELECTION_GAP to a value >= WHISK_EPOCHS_PER_SHUFFLING_PHASE - 1 disables tracker shuffling

[asn-d6]

Thanks!

[hwwhww]

@dapplion

Also need to update the presets/<minimal,mainnet>/whisk.yaml files and config files