feat(plot): add plot.py utils

src/aliby/utils/plot.py

+#!/usr/bin/env jupyter
+"""
+Basic plotting functions for cell visualisation
+"""
+
+from matplotlib import pyplot as plt
+
+
+def plot_overlay(bg, fg, alpha=0.5, ax=plt) -> None:
+    ax.imshow(bg, cmap=plt.cm.gray, interpolation="none")
+    ax.imshow(fg, alpha=alpha, interpolation="none")
+    ax.axis("off")