Add type hints to feature detection

[freemansw1]

Partially resolves #75 for feature detection only and adds type hints to all function calls. At the same time, I also went through and dealt with some of the easier issues that pylint found.

I started this process in an effort to start to think through our xarray transition. It helped me think through where iris is actually used (which isn't often in feature detection).

Note that to get Literal to work, we will have to increase our Python requirement to 3.8. I think this is reasonable given that 3.7 is EOL and is no longer available to be installed through conda. 3.7 first came out in 2018, but its most recent release was this June. There are two alternatives if we don't want to do this: 1. require the typing_extensions package. This is a new requirement, and all new requirements should be scrutinized, but given that it is from python itself, I think there is a low risk for inclusion. 2. make the types for our options just str, which I think is less preferred.

In the absence of automated matrix testing, I've run tests on my local machine with Python 3.11 and 3.8, both of which pass. There are still a number of linting errors, but c'est la vie.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (85f8f3a) 56.35% compared to head (68447a4) 56.43%.

Additional details and impacted files

@@              Coverage Diff              @@
##           RC_v1.5.x     #337      +/-   ##
=============================================
+ Coverage      56.35%   56.43%   +0.07%     
=============================================
  Files             16       16              
  Lines           3384     3390       +6     
=============================================
+ Hits            1907     1913       +6     
  Misses          1477     1477              

Flag	Coverage Δ
unittests	56.43% <100.00%> (+0.07%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
tobac/feature_detection.py	84.43% <100.00%> (+0.22%)	⬆️

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[freemansw1]

I decided to reverse course and add typing_extensions as a requirement to preserve 3.7 support and because I think it's highly likely that we will need the backporting of typing features at some point.

[w-k-jones]

I'm pro removing python 3.7 support with the v1.6 update, but including typing_extensions is probably a good idea for now

[freemansw1]

I've switched this to a draft PR until we get 1.5.1 out. RC_v1.5.x currently lags RC_v1.5_hotfix.

[freemansw1]

With 1.5.1 out, I've marked this as ready for review. I think there's an argument to wait on this (and #341) until v1.6.0, but I think there is no harm in doing so with v1.5.2 as well.

[w-k-jones]

Looks good, my only query is regarding the typing of the min_h1, max_h1 etc... variables for PBCs

[JuliaKukulies]

Looks very good - also nice that you addressed some pylint issues in the same go!

[harrietgilmour]

I really like this addition! It all looks good and a great starting point for adding type hints to the rest of tobac (if that's still the plan).

[freemansw1]

Updated now that we have merged in #293

[freemansw1]

@JuliaKukulies did I get the type for the statistics right? If so, I will go ahead and merge.

[JuliaKukulies]

@JuliaKukulies did I get the type for the statistics right? If so, I will go ahead and merge.

Yes, looks good!