support oidc v2

[Nirupma-Verma]

Desired Outcome

• Support added for OIDC authenticator for Conjur CLI and UI
• Readme updated

Implemented Changes

Describe how the desired outcome above has been achieved with this PR. In
particular, consider:

• Support added for OIDC authenticator for Conjur CLI and UI
• Readme updated

Connected Issue/Story

Resolves #[relevant GitHub issue(s), e.g. 76]

CyberArk internal issue ID: [insert issue ID]

Definition of Done

At least 1 todo must be completed in the sections below for the PR to be
merged.

Changelog

• The CHANGELOG has been updated, or
• This PR does not include user-facing changes and doesn't require a
  CHANGELOG update

Test coverage

• This PR includes new unit and integration tests to go with the code
  changes, or
• The changes in this PR do not require tests

Documentation

• Docs (e.g. READMEs) were updated in this PR
• A follow-up issue to update official docs has been filed here: [insert issue ID]
• This PR does not require updating any documentation

Behavior

• This PR changes product behavior and has been reviewed by a PO, or
• These changes are part of a larger initiative that will be reviewed later, or
• No behavior was changed with this PR

Security

• Security architect has reviewed the changes in this PR,
• These changes are part of a larger initiative with a separate security review, or
• There are no security aspects to these changes

[szh]

This is looking good. Needs some CodeClimate fixes, a Changelog entry, and tests.

[szh]

I'm reviewing this week, but please also look at the CodeClimate issues.

[szh]

I left a few suggestions for minor fixes. Can we add an integration test to verify this works with an actual Conjur instance?

[andytinkham]

As we started discussing in the security review today and then I discussed further with @szh, I have concerns about how this fits in the concept of an API. It is not signed off pending further discussions I've asked @itsbrugu to set up.