Remove curl dependency and disable OAuth Bearer SASL mechanism

The curl dependency is just necessary for the OAuth Bearer SASL mechanism. Let's remove that configuration option for now.

Removes the curl dependency.

Author: FranzBusch

Package.swift

@@ -72,7 +72,6 @@ let package = Package(
                 .define("_GNU_SOURCE", to: "1"),  // Fix build error for Swift 5.9 onwards
             ],
             linkerSettings: [
-                .linkedLibrary("curl"),
                 .linkedLibrary("sasl2"),
                 .linkedLibrary("z"),  // zlib
             ]

Sources/Crdkafka/custom/config/config.h

@@ -23,7 +23,7 @@
 #define ENABLE_ZSTD 1
 #define ENABLE_SSL 1
 #define ENABLE_GSSAPI 1
-#define ENABLE_CURL 1
+#define ENABLE_CURL 0
 #define ENABLE_DEVEL 0
 #define ENABLE_VALGRIND 0
 #define ENABLE_REFCNT_DEBUG 0

Sources/Kafka/Configuration/KafkaConfiguration+Security.swift

@@ -309,7 +309,7 @@ extension KafkaConfiguration {
             }
         }
 
-        public struct OAuthBearerMethod: Sendable, Hashable {
+        struct OAuthBearerMethod: Sendable, Hashable {
             internal enum _OAuthBearerMethod: Sendable, Hashable {
                 case `default`(
                     configuration: String?
@@ -337,7 +337,7 @@ extension KafkaConfiguration {
             ///     For example: `principalClaimName=azp principal=admin scopeClaimName=roles scope=role1,role2 lifeSeconds=600`.
             ///     In addition, SASL extensions can be communicated to the broker via `extension_NAME=value`.
             ///     For example: `principal=admin extension_traceId=123`
-            public static func `default`(configuration: String? = nil) -> OAuthBearerMethod {
+            static func `default`(configuration: String? = nil) -> OAuthBearerMethod {
                 OAuthBearerMethod(_internal: .default(configuration: configuration))
             }
 
@@ -359,7 +359,7 @@ extension KafkaConfiguration {
             ///     - scope: The client uses this to specify the scope of the access request to the broker.
             ///     - extensions: Allow additional information to be provided to the broker.
             ///     Comma-separated list of key=value pairs. E.g., "supportFeatureX=true,organizationId=sales-emea".
-            public static func oidc(
+            static func oidc(
                 configuration: String? = nil,
                 clientID: String,
                 clientSecret: String,
@@ -419,7 +419,8 @@ extension KafkaConfiguration {
         }
 
         /// Use the OAUTHBEARER mechanism.
-        public static func oAuthBearer(method: OAuthBearerMethod) -> SASLMechanism {
+        // This is currently disabled since it requires a curl dependency otherwise.
+        static func oAuthBearer(method: OAuthBearerMethod) -> SASLMechanism {
             SASLMechanism(
                 _internal: .oAuthBearer(method: method)
             )