Support for OCI Vault

[amartyaa]

Is your feature request related to a problem? Please describe.
Oracle Cloud has a native vault. ArgoCD should be able to sync with it to fetch secrets.

Describe the solution you'd like
OCI Vault should be added as supported vault.

Describe alternatives you've considered
Not an alternate solution but I have used External Secrets Operator to create kubernetes secrets sourced from OCI Vault.

Additional context
I can work on development

[werne2j]

@amartyaa Thanks for the suggestion, we might not be able to get to this but feel free to put together a PR and we would be happy to review it

[ddevadat]

@werne2j created a PR for OCI vault support as a backend
#670