Added support for custom cookies

[Zonalds]

Hello,

I added support for logging in using custom cookies. Managing logging using password can be a headache. There is support for cached cookies but not external cookies.

I added a support for external cookies using existing cookies that could be gotten from, say, chrome extensions.

it can be used as follows:

      await client.login(linkedInUsername, linkedInPassword, customCookies)

Let me know what you think.

[Ranork]

Looks cool! also thanks for clearing unnecessary spaces 😄

[Zonalds]

Awesome. It'd be great to update the NPM package ^_^