When logging in to Terraform Cloud or Terraform Enterprise, change the
success output to be a bit more customized for the platform. For
Terraform Cloud, fetch a dynamic welcome banner that intentionally fails
open and defaults to a hardcoded message if its not available for any
reason.
When a token is pasted by the user, we make a request to the
TFE API /account/details endpoint to verify its validity. If successful,
we display the logged-in username as confirmation. If not, we refuse to
store the invalid token and display an error message.
This commit also trims whitespace from around the pasted value, to
reduce the likelihood of a copy & paste error.
Chris Arcand