MINOR: Add support for ACME challenge dns-persist-01

In this case, like for http-01, dataplaneapi only takes core of saving
the certificate to disk.

Author: oliwer

models/acme_provider.go

@@ -12077,10 +12077,11 @@ definitions:
         x-nullable: true
         x-omitempty: true
       challenge:
-        description: ACME challenge type. Only http-01 and dns-01 are supported.
+        description: ACME challenge type.
         enum:
           - http-01
           - dns-01
+          - dns-persist-01
         type: string
       challenge_ready:
         description: |

specification/build/haproxy_spec.yaml

@@ -29,8 +29,8 @@ acme:
       x-nullable: true
     challenge:
       type: string
-      enum: ['http-01', 'dns-01']
-      description: ACME challenge type. Only http-01 and dns-01 are supported.
+      enum: ['http-01', 'dns-01', 'dns-persist-01']
+      description: ACME challenge type.
     challenge_ready:
       type: array
       minItems: 1