[feature] Sampler near land

[b-barton]

Is your feature request related to a problem?

The simple sampler has not way to deal with a profile that is on land or next to land.

Describe the solution you'd like...

If the observation profile is between land and sea on the model grid take the sea point. If the observation profile is on land on the model grid return a masked profile and mark the profile as unusable. Do this in a similar way to the out of time bounds profiles where the profiles are subset #9 .

Describe any alternatives you've considered...

No response

Additional context

No response

[b-barton]

I've witten code and a test to account for profiles that are on model grid land points and not extracting a profile at them. This has ben done for the ij index functions and the geoballtree functions.