Adds desktop context menu (#503, #568)

[holmesworcester]

Adds a context menu in Quiet desktop for copying text (#503) and saving images (#503)

This adds a small tweak from an earlier PR (#2355) by @agiledev24 to keep the new change from breaking unit tests.

Thank you @agiledev24 for your contribution!

Pull Request Checklist

• I have linked this PR to a related GitHub issue.
• I have added a description of the change (and Github issue number, if any) to the root CHANGELOG.md.

[holmesworcester]

@islathehut -- this fails dependency review, but the dependency seems to be used by a lot of electron-related packages, not the one added by this PR. how do you suggest I proceed?

Also, it looked like it could be tricky to include the context-menu in the unit tests, and that the value could be limited, since this seems like a "set and forget" feature that will not interact much with other features--at least not until we start using the context menu ourselves for our own particular functions.

It also seemed like this was not the best place to learn about mocks and tests, but maybe I'm wrong about that.

What do you think? Want to make me write a test for this?

[islathehut]

@islathehut -- this fails dependency review, but the dependency seems to be used by a lot of electron-related packages, not the one added by this PR. how do you suggest I proceed?

Also, it looked like it could be tricky to include the context-menu in the unit tests, and that the value could be limited, since this seems like a "set and forget" feature that will not interact much with other features--at least not until we start using the context menu ourselves for our own particular functions.

It also seemed like this was not the best place to learn about mocks and tests, but maybe I'm wrong about that.

What do you think? Want to make me write a test for this?

@holmesworcester I wouldn't worry about the dependency review, especially if its on electron since we're not gonna be upgrading that right now.

For tests this may be a good candidate for e2e tests.