Handle saving files without extensions

[btargac]

• will add the extension retrieved from mime-type / Content-type header from the http response
• will avoid over writing the existing files if there are multiple urls with the exact same path
• get rid of optional chaining plugin of babel, since its included in the core modules of babel
• update browserlist file to reduce the number of polyfills added to the bundle
• and as always update some dependencies

[codecov]

Codecov Report

Merging #54 (bdea888) into master (d15dd2e) will increase coverage by 5.47%.
The diff coverage is 30.76%.

@@            Coverage Diff             @@
##           master      #54      +/-   ##
==========================================
+ Coverage   13.04%   18.51%   +5.47%     
==========================================
  Files           1        2       +1     
  Lines          46       54       +8     
  Branches        5        6       +1     
==========================================
+ Hits            6       10       +4     
- Misses         35       39       +4     
  Partials        5        5              

Impacted Files	Coverage Δ
src/utils/processItems.js	13.72% <10.00%> (+0.68%)	⬆️
src/utils/generateFileName.js	100.00% <100.00%> (ø)

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