Add waterquality (substance/concentration) tables

[evetion]

Fixes #1125. Split from #1137

[evetion]

There can be some bike shedding on the table names, but the tables are all required. Ideally we merge this soon, so we prevent a huge PoC merge later on, as discussed in our retro.

[visr]

Haven't had a look yet, but does this already incorporate the comments on #1125?

[visr]

BasinBoundaryConcentration

[evetion]

Nope, that breaks some generation in the Julia code.

[visr]

@version BasinConcentrationV1 begin
    node_id::Int32
    time::DateTime
    substance::String
    basin::Union{Missing, Float64}  # optional, for external calculations
    drainage::Union{Missing, Float64}
    precipitation::Union{Missing, Float64}
end

[evetion]

After an extensive discussion with @visr, we arrived at the current setup, with split out table for the basin.

For generating concentrations (whether with Delwaq, internal) we need an initial state and boundary conditions. For control on concentrations, we only need a timeseries. Catering to both needs is complex and confusing, so we now decided to split them all out. The External table can be refactored into an external node once the functionality and/or internal concentration calculations are there.