4092 [in_app_purchase] Add documentation for price change confirmations (cla: yes, waiting for tree to go green, p: in_app_purchase)

4096 [in_app_purchase] Fix app exceptions caused by missing App Store receipt (cla: yes, waiting for tree to go green, p: in_app_purchase, platform-ios)

4113 [in_app_purchase] Initialize SKError with correct data type (cla: yes, waiting for tree to go green, p: in_app_purchase, platform-ios)

4114 [in_app_purchase] Added priceCurrencySymbol to SkuDetailsWrapper (cla: yes, waiting for tree to go green, p: in_app_purchase, platform-android)

4115 [in_app_purchase] Add currencySymbol to ProductDetails (cla: yes, waiting for tree to go green, p: in_app_purchase)