[Dart] Fix authentication for HTTP basic, API keys

[dalewking]

Description of the PR

See #2396

The only authentication scheme that was actually usable on dart was oauth. These changes to allow using ApiKeyAuth and basic authentication. It also takes the step that when the access information is set it isn't in public properties so cannot be simply read.

@ircecho @swipesight @jaumard

[auto-labeler]

👍 Thanks for opening this issue!
🏷 I have applied any labels matching special text in your issue.

The team will review the labels and make any necessary changes.

[dalewking]

Closing and re-opening to kick Travis to build again

[wing328]

Thanks for the PR but your commit (as shown in the Commits tab) is not linked to your Github account, which means this PR won't count as your contribution in https://github.com/OpenAPITools/openapi-generator/graphs/contributors.

Let me know if you need help fixing it.

Ref: https://github.com/OpenAPITools/openapi-generator/wiki/FAQ#how-can-i-update-commits-that-are-not-linked-to-my-github-account

[cedricziel]

Added a small PR to your branch (dalewking#1). This incorporates your changes into the top-level README and expands the basic auth so it's easier to use.

[dalewking]

Thanks for the PR but your commit (as shown in the Commits tab) is not linked to your Github account

Amended the commits and fixed. Was using my work email address

[wing328]

The new commits are correctly linked to your account You can also add your work email address as the secondary email address in the Github account so that the first 2 commits are correctly linked to your account.