Add support for simple row filters to `h5x`

[jpswinski]

Allow the user to supply a simple filter to h5x requests where each row of the dataframe is conditioned on the value of a given column being either:

• in a range
• out of a range
• included in a set
• not included of a set

We could also support a list of filters.

[jpswinski]

Given the ability to supply the geo columns in the request, the api could also support spatial and temporal subsetting.

[jpswinski]

Will need some way to autodetect time8 fields in the h5 variable dataset module.