Add [NpmStatDownloads] Badge (#9783)

* feat: add npm downloads (by author) badge

* Update services/npm-stat/npm-stat-downloads.service.js

Co-authored-by: chris48s <chris48s@users.noreply.github.com>

* test: add test cases for NpmStatDownloads helper getTotalDownloads

* refactor: using dayjs to get from && until date string

* feat: remove support of dt

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Co-authored-by: chris48s <chris48s@users.noreply.github.com>