feat: implement startPosition (#3355)

* feat(android): implement startPosition

* feat(ios): implement startPosition

* feat: implement startPosition type

* docs: fix typo

* docs: update startPosition

* refactor: put startPosition inside source prop
- put startPosition inside source prop
- rename existing prop (startTime, endTime)

* docs: update startPosition property description

* fix: fix invalid assignments

* refactor: remove redundant optional chaining

* feat: allow "0" to work too

ios/Video/DataStructures/VideoSource.swift

@@ -6,8 +6,9 @@ struct VideoSource {
     let isAsset: Bool
     let shouldCache: Bool
     let requestHeaders: Dictionary<String,Any>?
-    let startTime: Int64?
-    let endTime: Int64?
+    let startPosition: Int64?
+    let cropStart: Int64?
+    let cropEnd: Int64?
     // Custom Metadata
     let title: String?
     let subtitle: String?
@@ -25,8 +26,9 @@ struct VideoSource {
             self.isAsset = false
             self.shouldCache = false
             self.requestHeaders = nil
-            self.startTime = nil
-            self.endTime = nil
+            self.startPosition = nil
+            self.cropStart = nil
+            self.cropEnd = nil
             self.title = nil
             self.subtitle = nil
             self.description = nil
@@ -40,8 +42,9 @@ struct VideoSource {
         self.isAsset = json["isAsset"] as? Bool ?? false
         self.shouldCache = json["shouldCache"] as? Bool ?? false
         self.requestHeaders = json["requestHeaders"] as? Dictionary<String,Any>
-        self.startTime = json["startTime"] as? Int64
-        self.endTime = json["endTime"] as? Int64
+        self.startPosition = json["startPosition"] as? Int64
+        self.cropStart = json["cropStart"] as? Int64
+        self.cropEnd = json["cropEnd"] as? Int64
         self.title = json["title"] as? String
         self.subtitle = json["subtitle"] as? String
         self.description = json["description"] as? String