Translate src/cli/upgrade-plugins.ts from JS to TS

[Isaachristian]

This pull request translates src/cli/upgrade-plugins.ts from javascript to typescript. This resolves #143.

[coveralls]

Pull Request Test Coverage Report for Build 7720664893

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.02%) to 85.108%

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Totals
Change from base Build 7649102120:	0.02%
Covered Lines:	22628
Relevant Lines:	25350

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💛 - Coveralls