feat: can directly specify the path of sdk

lua/flutter-tools/executable.lua

@@ -126,9 +126,16 @@ function M.get(callback)
     end
   end
 
+  local flutter_sdk_path = nil
+  if config.flutter_sdk then flutter_sdk_path = flutter_sdk_path end
+
   if config.flutter_path then
-    local flutter_path = fn.resolve(config.flutter_path)
-    _paths = { flutter_bin = flutter_path, flutter_sdk = _flutter_sdk_root(flutter_path) }
+    local flutter_path = config.flutter_path
+    local flutter_path_real_try = fn.resolve(flutter_path)
+    _paths = {
+      flutter_bin = flutter_path,
+      flutter_sdk = flutter_path or _flutter_sdk_root(flutter_path_real_try),
+    }
     _paths.dart_sdk = _dart_sdk_root(_paths)
     _paths.dart_bin = _flutter_sdk_dart_bin(_paths.flutter_sdk)
     return callback(_paths)