Handle Generate Password in App.js

This issue should be resolved by creating handleGeneratePassword that:

if
not includeUpperCase and not includeLowerCase and not includeNumbers and not includeSymbols
then notify error

else
let characterList = ""
if includeNumbers is true
characterList = characterList + numbers
if includeUpperCase is true
characterList = characterList + upperCaseLetters
.
.
.
Set Password createPassword pass characterList
notify

从 App.js 开始，找到密码生成控件、createPassword 调用以及现有的通知行为。实现 issue 中描述的 handleGeneratePassword 流程，包括未选择任何字符时的错误处理和已选择的字符组，然后验证在每种选择情况下生成和通知都能正常工作。

由索引模型根据 Issue 内容生成。