chore: add additional exports for elements to be seen by typedoc

[EscapedGibbon]

add exports for filterPoints and getExtrema so they could be added to typedoc generated documentation.

[codecov[bot]]

Codecov Report

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

Comparison is base (58041ea) 98.58% compared to head (1dccf05) 98.58%. Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #412 +/- ## ======================================= Coverage 98.58% 98.58% ======================================= Files 223 224 +1 Lines 5848 5850 +2 Branches 1239 1238 -1 ======================================= + Hits 5765 5767 +2 Misses 80 80 Partials 3 3 ```

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[stropitek]

add exports for filterPoints and getExtrema so they could be added to typedoc generated documentation.

The main reason for this change is to make those functions available publicly for anyone who installed the library to use. It being in typedoc is a side effect of that.

[lpatiny]

Maybe we could rename the method filterPoints to be lest generic and actually give as name what is does: removeClosePoints.

  const points = getExtrema(image, {kind: 'maximum'});
  const distinctPoints = removeClosePoints(points, {distance: 5, kind: 'maximum'});