[quick-open] Do not validate input on start

[vinokurig]

What it does

Check if the onType handler is fired at first time, ignore validating the input. As QuickInputService wraps QuickOpenServece:

theia/packages/core/src/browser/quick-open/quick-input-service.ts

Line 123 in 5e50106

this.quickOpenService.open({

such workaround can resolve the problem.
fixes #6245

How to test

1. Clone and compile the test plugin
2. Start the plugin as a Hosted Plugin
3. F1 => Hello World

See: The validation is not called on the start.

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

[JPinkney]

LGTM

[akosyakov]

@vinokurig Does it close any issues? Could you reference them please?

[vinokurig]

@akosyakov

Does it close any issues? Could you reference them please?

Updated description.

[akosyakov]

works nicely for me too