oraclecloud: extended zone detection

[ldez]

Adds the option OCI_EXTENDED_ZONE_DETECTION.

How to test this PR?

1. You need Go
2. Checkout the PR:

   git clone https://github.com/ldez/lego.git
   cd lego
   git checkout feat/dns/oraclecloud/zone-detection

3. Compile lego:
   • if you have make: make build
   • if you don't make make: go build -o dist/lego ./cmd/lego
4. Run the following command with your information (email, domain, credentials, etc.):

   OCI_EXTENDED_ZONE_DETECTION=true \
   ...
   ./dist/lego -m your_email@example.com --dns oraclecloud -d '*.example.com' -d example.com -s https://acme-staging-v02.api.letsencrypt.org/directory run

5. Before each run of the command, you should clean your local environment:

   rm -rf .lego

Related to #2626