Support configuration of a resourcePreset

[jennydaman]

Our aim is to have the chart fnndsc/chris to work with zero (or minimal) config, but to also be flexible. While the best practice for production is still to manually define resources.requests and resources.limits for CPU and memory, we should also support setting these to reasonable values based on a human-readable preset name. e.g. if .Values.cube.resourcesPreset is set to large then the default resource limit for every service should be 1CPU.

Inspired by https://github.com/bitnami/charts/blob/973a2792e0bc5967e3180c6d44eebf223b9f1d83/bitnami/common/templates/_resources.tpl#L15-L43