added ca_cert_file and insecure_skip_verify in https connection.

[balsmn]

trafficstars

This PR enables to use the provider from behind a proxy which then uses a custom certificate. Now one can add either the proxy certificates to the newly introduced provider config ca_cert_file or can set to ignore certificate invalid error using the config variable insecure_skip_verify

[risicle]

For now we're manually pushing branches to our own fork to trigger CI runs, see https://github.com/alphagov/terraform-provider-concourse/actions/runs/383571073 to see how this goes...

Incidentally, it would be great if you could think of some way of adding basic tests for this feature, but I realize it's not particularly easy to test "fully".

Edit: currently fails with

pkg/client/client.go:13:2: use of internal package google.golang.org/protobuf/internal/errors not allowed

[risicle]

https://github.com/alphagov/terraform-provider-concourse/runs/1458178597?check_suite_focus=true#step:5:109 setup_test.go needs to be modified to supply the new arguments to client.NewConcourseClient.

BTW these tests are just straightforward github workflows, if should be easy for you to get them running on your own fork.

[balsmn]

Thanks for the hint. I will try to complete the integration test.

[MartinSchmidt123]

I am not sure I can help here but I would also be interested in getting this merged.