Expose isFileDoesNotExist and improve CI tests

[LoicPoullain]

Issue

• isFileDoesNotExist is not exported in @foal/storage.
• lerna run test is a bit slow and, when a test fails in Github Actions, it is difficult to know which one it is.

Solution and steps

• Export isFileDoesNotExist
• Do not use lerna run test in Github Actions

Checklist

• Add/update/check docs (code comments and docs/ folder).
• Add/update/check tests.
• Update/check the cli generators.

[codecov]

Codecov Report

Merging #657 into v1-7-0 will increase coverage by 0.25%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           v1-7-0     #657      +/-   ##
==========================================
+ Coverage   99.37%   99.62%   +0.25%     
==========================================
  Files          67       90      +23     
  Lines        1114     1591     +477     
  Branches      269      337      +68     
==========================================
+ Hits         1107     1585     +478     
+ Misses          7        6       -1     

Impacted Files	Coverage Δ
packages/core/src/core/routes/utils.ts	100.00% <0.00%> (ø)	⬆️
packages/core/src/express/not-found.ts	100.00% <0.00%> (ø)	⬆️
packages/core/src/express/create-app.ts	100.00% <0.00%> (ø)	⬆️
packages/core/src/sessions/constants.ts	100.00% <0.00%> (ø)	⬆️
packages/core/src/express/send-response.ts	100.00% <0.00%> (ø)	⬆️
packages/core/src/core/http/http-methods.ts	100.00% <0.00%> (ø)	⬆️
packages/core/src/common/utils/escape-prop.ts	100.00% <0.00%> (ø)	⬆️
packages/core/src/common/utils/render.util.ts	100.00% <0.00%> (ø)	⬆️
packages/core/src/openapi/utils/merge-tags.ts	100.00% <0.00%> (ø)	⬆️
packages/core/src/common/utils/validate.util.ts	100.00% <0.00%> (ø)	⬆️
... and 50 more

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