Coerce field names to string

[jaydenseric]

Fixes https://github.com/octet-stream/form-data/issues/22 .

Field name arguments of get, getAll, set, append, and delete are now coerced to string, like how native FormData implementations behave.

Also, while I was in the area I tidied some typos, etc. in the test names.

[codecov[bot]]

Codecov Report

Merging #23 into master will decrease coverage by 0.74%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #23      +/-   ##
==========================================
- Coverage   99.62%   98.88%   -0.75%     
==========================================
  Files          17       17              
  Lines         269      269              
  Branches       70       70              
==========================================
- Hits          268      266       -2     
- Misses          1        3       +2     

Flag	Coverage Δ
#unittests	98.88% <100.00%> (-0.75%)	:arrow_down:

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Impacted Files	Coverage Δ
src/lib/FormData.mjs	98.51% <100.00%> (-1.49%)	:arrow_down:

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[octet-stream]

I will release this today later, once I have a time to cut the release. Thanks again!

[jaydenseric]

Looking forward to this being released, so I can remove some workarounds in apollo-upload-client before I publish an update soon:

https://github.com/jaydenseric/apollo-upload-client/blob/302051fd04d9854fa04f985ab94e99b91a425e92/test/public/createUploadLink.test.js#L424-L426

[octet-stream]

Totally forgot to publish the release. Sorry. It is available now.