fix StaticProperty.subject: use stored property instead of computed to avoid allocating a new subject on every access

Amp-Thread-ID: https://ampcode.com/threads/T-019d1236-110d-717d-b5cc-faefb53720a3
Co-authored-by: Amp <amp@ampcode.com>

Author: lhoward

Sources/SwiftOCA/OCC/ControlClasses/Root.swift

@@ -313,6 +313,13 @@ public extension OcaRoot {
     var setMethodID: OcaMethodID? { nil }
     var propertyIDs: [OcaPropertyID]
     var value: T
+    let subject: AsyncCurrentValueSubject<PropertyValue>
+
+    init(propertyIDs: [OcaPropertyID], value: T) {
+      self.propertyIDs = propertyIDs
+      self.value = value
+      subject = AsyncCurrentValueSubject(.success(value))
+    }
 
     func refresh(_ object: SwiftOCA.OcaRoot) async {}
     func subscribe(_ object: OcaRoot) async {}
@@ -325,10 +332,6 @@ public extension OcaRoot {
       OcaProperty<Value>.PropertyValue.success(value)
     }
 
-    var subject: AsyncCurrentValueSubject<PropertyValue> {
-      AsyncCurrentValueSubject(currentValue)
-    }
-
     @_spi(SwiftOCAPrivate) @discardableResult
     public func _getValue(
       _ object: OcaRoot,