Credentials need to be more dynamic

[cloudnautique]

The current credential framework requires a credential once it has been added to a tool. This works in specific use cases, but as a tool publisher there are scenarios where you want some dynamic controls.

For instance, some APIs support both OAUTH2 and API tokens. Depending on the organization, user, and configuration a user should be able to select the choice that they want to use.

In the case of the UI or cli, the ability to specify the auth mechanism at run time is required.

Additionally, in some cases you might be using a tool locally with a development instance where there is no password. Having the ability to completely disable the credential providers at run time would also be useful.