Add launch on login feature

[Xaeroxe]

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Description

Linting of dependencies doesn't succeed. No dependencies were changed in this PR, so this must be a fairly recent problem.

Fixes #1653 and adds an option to the settings menu that launches Signal on startup.

No new unit tests were added. This has been tested on Windows 10. Other operating systems are assumed to work because the feature is based on this electron API which the author assumes is well tested.

[hiqua]

@Xaeroxe regarding linting, the problem is that there are exceptions for certain lines that don't apply anymore with new code, so these lines have to be changed.

For me so far, the simplest way to do this has been to just remove the whole exception file, then run yarn ready and copy-paste the "questionable lines" output as the exception file.

You might need to run ts/util/lint/sort_exceptions.ts after that to have a similar order.

After that you should have a somewhat minimal diff which should be small enough to inspect manually.

The exception file is: ts/util/lint/exceptions.json

[EvanHahn-Signal]

This change looks great! I'm going to merge it into a temporary branch, make a couple of small changes (including fixing the errors in exceptions.json), and get this released.

[EvanHahn-Signal]

We'll plan to release this in 5.3.0 and possibly sooner.

[EvanHahn-Signal]

@Xaeroxe Ubuntu users on our latest beta aren't seeing this property persisted, which blocks us from being able to take this to production. Any chance you could take a look?

(If I don't hear back soon, I'll plan to dig into it myself.)

[Xaeroxe]

This feature as implemented won't work on Linux systems per the Electron documentation. Probably we should just hide the checkbox on those systems. Getting the feature working on Linux will likely require a different approach.

[EvanHahn-Signal]

@Xaeroxe That makes sense. Would you be able to open a PR in the next few hours to disable this checkbox for Linux users? If not, I can do it. (There's some urgency because it's blocking our ability to go to production.)

[Xaeroxe]

It'd probably be best if you took care of it as I imagine you'll be able to get it done faster

[EvanHahn-Signal]

Okay, I'll do that. Thanks for your help!