Use jaraco.collections for code re-use on CaseInsensitiveDict.

[jaraco]

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

Feature and Bugfix and code removal.

• What is the related issue number (starting with #)

#1231

• What is the current behavior? (You can also link to an open issue here)

CherryPy has its own limited implementation of a Case-Insensitive Dict.

• What is the new behavior (if this is a feature change)?

I was reviewing #1633, I realized I'd seen this pattern before... and built a general-purpose class for its purpose... and released it as a library for others to consume. This approach removes CherryPy's bespoke implementation, which has the reported deficiency, and replaces it with the proven class found in jaraco.collections.

[jaraco]

In light of #1671, this dependency is not allowed, so the functionality must be inlined before this PR can move forward in the current master.

[codecov]

Codecov Report

Merging #1654 into master will increase coverage by 0.86%.
The diff coverage is 81.25%.

@@            Coverage Diff            @@
##           master   #1654      +/-   ##
=========================================
+ Coverage   78.04%   78.9%   +0.86%     
=========================================
  Files         106     106              
  Lines       13798   15761    +1963     
=========================================
+ Hits        10769   12437    +1668     
- Misses       3029    3324     +295

[webknjaz]

This pull request fixes 1 alert - view on lgtm.com

fixed alerts:

• 1 for Non-callable called

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Comment posted by lgtm.com