feat: add command to open popup

[WofWca]

Advantages:

• More convenient to open the extension popup, for example, if you want to translate a manually imput text.
• In Chromium browsers if the extension "Site access" is set to "On click", this makes a great combination with the "Auto translate" feature. When you visit a site that you want to translate, you can do so by executing the shortcut.
• Generally good for keyboard users.

For reference, my extension has this as well, and I use it exclusively, it's very convenient
https://github.com/WofWca/jumpcutter/blob/d5727fed31bb3b1a654b76ddf38d90ebd6a384e2/src/manifest.json#L35C1-L47

Related: #266, #117 (comment)

[vitonsky]

Linguist already support shortcuts to translate page

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If you still need this feature, please create new issue first and describe your use case and let's discuss how it should works.
Then you can implement feature in this MR if you want, but we have to bind issue number for each pull request.

Keep in mind that UX principles in Linguist oblige us to make any shurtcuts are custumizable, not hardcoded

[WofWca]

If you still need this feature, please create new issue first

Is it OK to discuss it in #117?

but we have to bind issue number for each pull request.

TBH I don't like such a policy.

[vitonsky]

but we have to bind issue number for each pull request.

TBH I don't like such a policy.

This rule is necessary to ensure project maintainability, thus it is not for discuss and we have to obey this rule to pull request will accepted

[vitonsky]

If you still need this feature, please create new issue first

Is it OK to discuss it in #117?

Of course. But if you will implement only shortcut to open popup, we have to introduce new issue and bind it with your pull request