feat: enable it to open multiple files

[CatBraaain]

Enable it to open multiple files

It's possible to get all selected files when running open command from context menu on explorer.
Here is a related code snippet on Stack Overflow:

• VS Code extension api get all selected files
• How to obtain a list of selected files from the explorer pane of VS Code?

Test

1. Select two text files.
2. Run open command from context menu.
3. Two text files opened.
   

I'm very new to pull request, I welcome any feedback.

[sandcastle]

You should look at combining these parameters into one

[CatBraaain]

Thanks for reviewing.

Do you mean removing uri parameter and use only uris parameter like as below

  this.open(uris);
  ---
  private open(uris: vscode.Uri[] | undefined): void {

or combining two parameters into one as tuple like as below.

  this.open(uri, uris);
  ---
  private open(uriArgs: [vscode.Uri | undefined, vscode.Uri[] | undefined]): void {

If the former, it might be good but I am still not sure callback function always has uris parameter when it has uri parameter. Because it's not described clearly in reference.
What I found is only this as below.

Note 1: When a command is invoked from a (context) menu, VS Code tries to infer the currently selected resource and passes that as a parameter when invoking the command. For instance, a menu item inside the Explorer is passed the URI of the selected resource and a menu item inside an editor is passed the URI of the document.
vscode api reference

If the latter, I don't understand why.

If the other, could you explain me more detail.

[CatBraaain]

I found a case, when selecting folder, uri argument has a value, but uris argument is undefined.
so that we need both of uri and uris parameter in my opinion.