CSS-6244 Adds client ID and secret to the provider config.

[alesstimec]

Description

Added client ID and client secret to Juju provider config, which will allow terraform provider to log in to JAAS using these client credentials.

Updates Juju dependency to 3.5 that contains needed login changes.

Type of change

<What type of a change is this? Please keep one or more relevant lines from below and delete the others.>

• Other: login method change

Environment

• Juju controller version: 3.5

• Terraform version:

QA steps

Manual QA steps should be done to test this PR.

provider juju {}
...

Additional notes

<Please add relevant notes & information, links to mattermost chats, other related issues/PRs, anything to help understand and QA the PR.>

[hmlanigan]

This file: https://github.com/juju/terraform-provider-juju/blob/main/templates/index.md.tmpl needs updates to Authentication section related to this change. After run make docs to add the results.

The PR description has no QA steps.

Have you run the acceptance tests locally? Github is consistently getting failures on the lxd tests.

[cderici]

This LGTM, just completed manual QA against 3.4 and 3.5 and it went well, everything seems to be working fine.

I was able to provide and pass through the client_id and the client_secret just fine, and also the validation against mutual exclusivity with username/password seems to be working fine.

Though I couldn't test it against a real JAAS setup with Juju, I'll give it a green light, as i) I confirmed that the current functionality is working without any issues, ii) all the tests are passing, and iii) I imagine @alesstimec can confirm that it's working well on jaas as he's the one who needed this change in the first place.