Ability to configure TLS ciphers in oauth-proxy

1. Proposed title of this feature request
Ability to configure TLS ciphers in oauth-proxy

2. What is the nature and description of the request?
Certain ciphers are considered insecure and are requested to be dropped by the Federal Office for Information Security (Germany).

• BSI TR-02102-2
• Technical Guideline TR-02102-2 Cryptographic Mechanisms: Recommendations and Key Lengths

It's therefore requested to have a way to configure TLS ciphers in oauth-proxy based on either OpenShift Container Platform 4 Cluster-wide cryptographic policies or via custom configruation option to apply customization and only have approved ciphers served by oauth-proxy

3. Why does the customer need this? (List the business requirements here)
The ciphers considered secure by Federal Office for Information Security (Germany) are listed in BSI TR-02102-2 and companies in Germany are requested and recommended to follow these guidelines as strictly as possible to guarantee secure data exchange. Further in some areas the guidelines are mandatory to be followed and therefore customers have a need to comply accordingly with all tooling in use (including OpenShift Container Platform)

4. List any affected packages or components.
oauth-proxy