feat(api): implement __array__

[cpcloud]

This PR adds an implementation of __array__ for Column and Table expressions.

There's hardly any code here, but this gives the ability to plot ibis expressions out of the box.

Here's an example:

which yields this plot:

[cpcloud]

cc @jcmkk3, I think this is a good first step on the way to being able to interop with seaborn and possibly other libraries.

[codecov]

Codecov Report

Merging #4547 (504e103) into master (c2b635a) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #4547   +/-   ##
=======================================
  Coverage   92.53%   92.54%           
=======================================
  Files         183      183           
  Lines       19994    20002    +8     
  Branches     2961     2961           
=======================================
+ Hits        18502    18510    +8     
  Misses       1116     1116           
  Partials      376      376           

Impacted Files	Coverage Δ
ibis/backends/datafusion/compiler.py	96.83% <100.00%> (+0.04%)	⬆️
ibis/expr/types/generic.py	90.94% <100.00%> (+0.07%)	⬆️
ibis/expr/types/relations.py	94.39% <100.00%> (+0.03%)	⬆️

[gforsyth]

[github-actions]

Test Results

       6 files         6 suites   4m 27s ⏱️
3 172 tests 3 158 ✔️ 14 💤 0 ❌
9 510 runs  9 468 ✔️ 42 💤 0 ❌

Results for commit 504e103.