## Changes
Allow account client auth with environment variables when no
.databrickscfg file present
Makes the behaviour to be in line with WorkspaceClient auth.
## Tests
Added regression test
## Changes
If the caller running the test has one or more environment variables
that are used in the test already set, they can interfere and make tests
fail.
## Tests
Ran tests in `./cmd/root` with Databricks related environment variables
set.
## Changes
The previous implementation ran the risk of infinite looping for the
account client due to a mismatch in determining what constitutes an
account client between the CLI and SDK (see
[here](83443bae8d/libs/databrickscfg/profiles.go (L61))
and
[here](0fdc5165e5/config/config.go (L160))).
Ultimately, this code must never infinite loop. If a user is prompted
and selects a profile that cannot be used, they should receive that
feedback immediately and try again, instead of being prompted again.
Related to #726.
## Tests
<!-- How is this tested? -->
## Changes
This reduces the latency of every workspace command by the duration of a
single API call to retrieve the current user (which can take up to a
full second).
Note: the better place to verify that a request can be authenticated is
the SDK itself.
## Tests
* Unit test to confirm an the empty `*http.Request` can be constructed
* Manually confirmed that the additional API call no longer happens
Andrew Nester
Pieter Noordhuis