[improve] Add M-a/C-a event for QTMLineEdit

[JimZhouZZY]

What

Added support for Cmd+A / Ctrl+A key events in QTMLineEdit to select all text in the search toolbar.

Related: #2232

Why

Cmd+A / Ctrl+A is a native QLineEdit behavior in Qt. Supporting it improves usability by allowing users to quickly modify their search query. This standard interaction should not be ignored, I guess.

How to test your changes

1. Build the project.
2. Open the search toolbar using Cmd+f / Ctrl+f.
3. Enter any text.
4. Press Cmd+a / Ctrl+a to ensure all text is selected.

[JackYansongLi]

你的代码没有format，我们用的是clang-format-16。如果你是macOS可以

brew install llvm@16

然后再在mogan的根目录

bin/format

[JimZhouZZY]

你的代码没有format，我们用的是clang-format-16。如果你是macOS可以

brew install llvm@16

然后再在mogan的根目录

bin/format

好的

[JackYansongLi]

你的代码没有format，我们用的是clang-format-16。如果你是macOS可以
brew install llvm@16
然后再在mogan的根目录
bin/format

好的

记得检查下版本，我们强制使用这个版本的，macOS默认的版本太高了

clang-format --version                                                                                                                                        ─╯
Homebrew clang-format version 16.0.6

needs format

[JackYansongLi]

LGTM