Check for incompatibility of water tracers with various hydrology options

At least initially, we probably won't implement water tracers for all possible options. So we should have checks that abort if you're trying to run with water tracers with any incompatible options.

One likely incompatibility is with use_aquifer_layer. This is partly because of #596 but @swensosc described to me some other fundamental oddities of the aquifer layer (with water volume being diagnosed rather than explicit) that sound like they could make water tracers hard.

Start by locating the water-tracer setup and the checks that process hydrology options. Identify which hydrology configurations are incompatible, beginning with use_aquifer_layer and the context in issue #596. Done means unsupported combinations abort clearly before running, with coverage for each identified incompatibility.

Written by the indexing model from the issue text.