Remove basic authentication support from the Artifactory provider

[danielmkn]

#342
We think we need to remove basic authentication from the Artifactory Provider. Basic auth will be removed in the following Artifactory versions, so it's the right move.
This change is a part of a core product roadmap. Tokens can be scoped per user. Please read more in the official documentation:
Access token documentation
How to generate an Access token.
We want to know any ideas or concerns from the contributors' community! Please let us know what do you think.

[alexhung]

Basic auth is removed in v4.0.0