Opening Signal again should show/unihde older instance

[mpsdskd]

• I have searched open and closed issues for duplicates

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Bug description

If I click on the Signal Icon again/ hit the hot-key again/type the signal command again while another instance is already open it should show/unhide the running instance of signal instead of doing nothing.

Steps to reproduce

• Open Signal
• Minimize it (the usual way or to tray)
• Try opening it again

Actual result: Nothing happens, new instance of Signal tries to open itself and closes again with console output quitting; we are the second instance
Expected result: skype, thunderbird, musicplayers usually show the running instance of the program upon trying to open a new instance of that program

Platform info

Kubuntu 17.10
Signal Desktop v1.1.0-beta.4