fence_openstack: added --auth-plugin option to allow usage of app credentials instead of user credentials

[s0urc3c0d3]

This allows users to user Barbican to generate app creds and put them in the clouds.yml:

clouds:
  openstack:
    auth:
      auth_url: http://CLOUD_ENDPOINT:5000
      application_credential_id: "SOMEID"
      application_credential_secret: "SOMELARGESECRET"
    region_name: "RegionOne"
    interface: "public"
    identity_api_version: 3
    auth_type: "v3applicationcredential"

The app creds can have smaller perm from user and they can be easly generated by users instead of full cloud accounts

To user this feature user can run:
$ fence_openstack --cloud openstack -n INSTANCEUUID -o list --auth_plugin v3applicationcredential

[knet-ci-bot]

Can one of the admins verify this patch?

[oalbrigt]

Dont change these, as they're replaced to the path found by ./configure during make.

[oalbrigt]

Use - instead of _ to stay consistent with the rest of the agent.

[oalbrigt]

You'll also have to run make xml-upload to update the metadata and attach it to the PR, so it doesnt fail CI when running make xml-check.

[s0urc3c0d3]

ok thx for your time. I'm gonna fix the issues you pointed out and get back here :)

[knet-jenkins]

Can one of the admins check and authorise this run please: https://ci.kronosnet.org/job/fence-agents-pipeline/job/PR-533/1/input