fix: Make HookContext properties public (#45)

## This PR
- When writing a custom hook I notice that we cannot read the
`HookContext` properties.
- This PR is making all the `HookContext` properties public.

Signed-off-by: Thomas Poignant <[email protected]>
Co-authored-by: Nicklas Lundin <[email protected]>

Author: thomaspoignant

Sources/OpenFeature/HookContext.swift

@@ -2,10 +2,10 @@ import Foundation
 
 /// A data struct to hold immutable context that ``Hook`` instances use.
 public struct HookContext<T> {
-    var flagKey: String
-    var type: FlagValueType
-    var defaultValue: T
-    var ctx: EvaluationContext?
-    var clientMetadata: ClientMetadata?
-    var providerMetadata: ProviderMetadata?
+    public var flagKey: String
+    public var type: FlagValueType
+    public var defaultValue: T
+    public var ctx: EvaluationContext?
+    public var clientMetadata: ClientMetadata?
+    public var providerMetadata: ProviderMetadata?
 }