Add support for analytical czjzek distribution

[deepanshs]

Analytical expression for computing czjzek distribution

The syntax remains the same, but analytical model is preferred for distributions when available

czjzek = CzjzekDistribution(sigma=1.25,polar=True)

# default is analytics (~0.2 s)
x_dist1, y_dist1, amp1 = czjzek.pdf(pos=[x_range, y_range])

# to force numerical computation (~15.5 s)
x_dist0, y_dist0, amp0 = czjzek.pdf(pos=[x_range, y_range], analytical=False, size=10_000_000)

Comparison test