Replace fs.exists with other fileSystem alternatives

[shrirambalaji]

Type: chore
Scope: plugins/local-storage

The following has been addressed in the PR:

• There is a related issue? fs.exists is deprecated #60
• Unit or Functional tests are included in the PR - Yes

Description:

This PR removes our usage of fs.exists and replaces it with other file system API alternatives like fs.access and fs.stat.

Resolves #60

[juanpicado]

@sergiohgz I think the token just expired, it failed on publish

[codecov]

Codecov Report

Merging #159 into master will increase coverage by <.01%.
The diff coverage is 88.88%.

@@            Coverage Diff             @@
##           master     #159      +/-   ##
==========================================
+ Coverage   65.29%   65.29%   +<.01%     
==========================================
  Files          25       25              
  Lines        1386     1389       +3     
  Branches      198      199       +1     
==========================================
+ Hits          905      907       +2     
- Misses        479      480       +1     
  Partials        2        2

Flag	Coverage Δ
#core	88.18% <ø> (ø)	⬆️
#plugins	58.48% <66.66%> (-0.06%)	⬇️

Impacted Files	Coverage Δ
plugins/memory/src/memory-handler.ts	87.17% <88.88%> (-0.83%)	⬇️

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[juanpicado]

Thanks guys !!