feat: ask selected code block (#39)

lua/avante/selection_result.lua

@@ -0,0 +1,17 @@
+--@class avante.SelectionResult
+--@field content string Selected content
+--@field range avante.Range Selection range
+local SelectionResult = {}
+SelectionResult.__index = SelectionResult
+
+-- Create a selection content and range
+--@param content string Selected content
+--@param range avante.Range Selection range
+function SelectionResult.new(content, range)
+  local self = setmetatable({}, SelectionResult)
+  self.content = content
+  self.range = range
+  return self
+end
+
+return SelectionResult