Added the file/newFile menu including menu entries

[jonah-iden]

What it does

Fixes #12755

this adds the new file/newFile independent submenu which is used by extensions to contribute creation of new files with specific types.
The Menu is then used by the new File->New File... menu entry

Buttons to change keybindngs for the contributed new file commands are currently missing.
Out of some reason i couldn't find the commands in the keybindings

How to test

Best to test is probably with the Python extension

1. install Python extension
2. go to File->New File...
3. A quickpick should open with different file types
4. Select New Python File and see a new untitled .py file is created

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with the review guidelines

[msujew]

VSCode displays things a bit differently:

Looking at the registered command, it seems they are using the shortTitle of the command as the label of the quick pick item:

{
  "title": "%python.command.python.createNewFile.title%", <-- "New Python File"
  "shortTitle": "%python.menu.createNewFile.title%", <-- "Python File"
  "category": "Python",
  "command": "python.createNewFile"
},

Also, the item seemed to be grouped by a group attribute of the registered menu entry. See here.

I think we should align to their design, which is a bit more focused on the actual file types than on the names of the commands.

On another note, I believe that the playwright tests need to be changed a bit.

[jonah-iden]

yup have seen the playwright tests.
Regarding short title and group, there seemed to be some problems regarding getting those on frontend side. But i can look again tomorrow if i overlooked something

[jonah-iden]

it seems like there is currently no support in theia for both the groupand the shortTile attribute. Maybe we should create a new issue for that

[msujew]

@jonah-iden Can you create an issue for that and add the link to the showNewFilePicker method as a @todo? Afterwards I think this should be good to go 👍

[jonah-iden]

here is the issue #12824

[msujew]

Alright, with #12824 in mind, this looks good to me 👍

[vince-fugnitto]

LGTM 👍