feat: Add equality to Email

[mcintyre94]

Checklist

• I have made a material change to the repo (functionality, testing, spelling, grammar)
• I have read the [Contribution Guide] and my PR follows them.
• I updated my branch with the master branch.
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation about the functionality in the appropriate .md file (I don't think any is relevant, but happy to add anything appropriate if I've missed it)
• I have added in line documentation to the code I modified

Short description of what this PR does:

Email objects are defined as equal iff they have the same email and the same name.
This is useful for unit tests where we want to verify that the Email objects generated are as expected.

[SendGridDX]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #739 into master will increase coverage by 0.06%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #739      +/-   ##
==========================================
+ Coverage   82.41%   82.48%   +0.06%     
==========================================
  Files          70       70              
  Lines        2303     2312       +9     
  Branches      338      340       +2     
==========================================
+ Hits         1898     1907       +9     
  Misses        206      206              
  Partials      199      199              

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[eprykhodko]

If, I may point out, this makes Email objects unhashable, which is inconvenient in some cases. For example getting rid of duplicates in a list of cc's. I suppose this should be considered a regression and should be fixed up?

[childish-sambino]

@eprykhodko Ack, taking a look. This was definitely not the intent.

[childish-sambino]

I'm just gonna roll this back. The original change was when the Email class only contained an email address and a name. Later (I don't understand why) other fields were introduced including a subject, substitutions, and a personalization.