Add calculation of point-to-point distance

[cchwala]

This PR provides the following

• an implementation to project point coordinates from lon-lat to a defined coordinate system
• an example notebook to calc distances and select closest neighbors (currently using PWS data that is downloaded in the notebook)
• info on our data model in the docs

check:

• [x] implement #15 for point data
• [x] Tests added and passed if fixing a bug or adding a new feature
• [x] All code checks from pre-commit passed

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (a64b787) 100.00% compared to head (7999aa1) 100.00%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #16 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 2 3 +1 Lines 20 43 +23 ========================================= + Hits 20 43 +23 ```

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