Add isort to organize dependency imports

[natestemen]

Description

This PR adds isort as a dependency. isort is short for "import sort" and sorts dependencies (both alphabetically in each import statement, and groups them according to standard library -> 3rd party -> 1st party imports) in each python file. In addition this PR adds isort to run both as part of CI via the makefile and adds config for it to run properly in our pyproject.toml file.

Motivation

I've made some version of this comment more than twice now, so easiest just to automate away the conversation!

[github-actions]

👈 Launch a binder notebook on branch unitaryfund/mitiq/nts-isort

[codecov]

Codecov Report

Merging #1959 (9416d1b) into master (06f82af) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1959   +/-   ##
=======================================
  Coverage   98.39%   98.39%           
=======================================
  Files          83       83           
  Lines        3869     3873    +4     
=======================================
+ Hits         3807     3811    +4     
  Misses         62       62           

Files Changed	Coverage Δ
mitiq/benchmarks/ghz_circuits.py	100.00% <ø> (ø)
mitiq/benchmarks/qpe_circuits.py	100.00% <ø> (ø)
mitiq/benchmarks/mirror_circuits.py	98.50% <100.00%> (ø)
mitiq/benchmarks/mirror_qv_circuits.py	100.00% <100.00%> (ø)
mitiq/benchmarks/quantum_volume_circuits.py	100.00% <100.00%> (ø)
mitiq/benchmarks/randomized_benchmarking.py	95.00% <100.00%> (ø)
mitiq/benchmarks/w_state_circuits.py	100.00% <100.00%> (ø)
mitiq/calibration/calibrator.py	98.18% <100.00%> (ø)
mitiq/calibration/settings.py	99.43% <100.00%> (ø)
mitiq/cdr/_testing.py	69.23% <100.00%> (ø)
... and 42 more

[andreamari]

Cool!