[Feature request] ignoreSelection by language/Glob/FileExtension ?

**Is your feature request related to a problem? Please describe.**
Description of what the problem is. Ex. I'm always frustrated when [...]

在我的使用中,有的编程语言我希望能够 运行选中的代码片段,有的语言又不希望能运行选中(在编写脚本时可能会因为经常选中文本而导致运行出错)

**Describe the solution you'd like**
Description of what you want to happen.
增加几个设置项,支持类似如下map
```
"code-runner.ignoreSelectionByFileExtension": {
".py": true,
".bat": false
}
```