Regional filtering

[HaleySchuhl]

Is your feature request related to a problem? Please describe.
Treating an entire image with a filter, such as blurring, there is a trade off between cleaning false-positives from a mask and creating false-negatives (missing pixels in the plant mask).

Describe the solution you'd like
Be able to provide a region of interest for morphological functions like fill, fill_holes, closing, dilate, erode, floodfill, gaussian_blur, laplace_filter, median_blur, opening, scharr_filter, sobel_filter, stdev_filter, and possibly a couple others including filters on size/eccentricity pcv.filters.obj_props. For simplicity, the region should be a rectangle. Apply the same logic to pcv.transform.detect_color_card.

Describe alternatives you've considered
Adding a region filter function that takes a rectangular region (x, y, h, w) and the name of the filter function and keyword arguments that get passed to the filter function. Option to apply to only WITHIN or only OUTSIDE of the rectangle.

• (less favored) adding ROI option (default: None) to all the functions and implementing a helper function to enable the functionality.

Additional context
Some functions are slow, like pcv.theshold.texture it's computationally heavy to calculate so reducing the area it's applied could make workflows faster.