Typescript & Promises

[morrys]

Issue #, if available:
#123
#162
#171

Description of changes:

hi all, I would like to ask your opinion about this PR I created where I made these changes:

javascript to typescript
possibility to use promises or userhandler functions
test with jest

Thanks

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[morrys]

Hi, I published the version on npm, so you can test it and evaluate it better.
npm i amazon-cognito-auth-ts
https://github.com/morrys/amazon-cognito-auth-ts