Support --restart flag on Windows

[walfie]

I originally tried to implement this on Windows but wasn't able to get it working well. Closing the Stream Deck application works fine with Command::new("taskkill").args(&["/f", "/im", "StreamDeck.exe"]).status(), but reopening it had issues.

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Doing it this way causes the CLI command to hang since it waits for StreamDeck.exe to return:

streamdeck-youtube-emotes/src/main.rs

Line 242 in 3e527e5

Command::new(r#"C:\Program Files\Elgato\StreamDeck\StreamDeck.exe"#).status()

Doing it this way causes the error Windows cannot find 'C:\Program':

streamdeck-youtube-emotes/src/main.rs

Lines 199 to 201 in 106f0f7

	Command::new("start")
	.args(&["", r#"C:\Program Files\Elgato\StreamDeck\StreamDeck.exe"#])
	.status()

Adding quotes around it doesn't work either (I guess it includes the quotes as part of the path?)

streamdeck-youtube-emotes/src/main.rs

Lines 241 to 243 in 2a60a0c

	Command::new("start")
	.args(&["", r#""C:\Program Files\Elgato\StreamDeck\StreamDeck.exe""#])
	.status()

Looks like it's related to a longstanding issue regarding escaping in Windows commands:
rust-lang/rust#29494 (The fix is only available on nightly)

A proposed workaround (that works on stable rust) is to use some Windows-specific functions, but I don't have a Windows device to test on, and this flag is just a "nice to have" (the user can just close and reopen the application themselves) so I'll leave this one to someone else who wants to send a PR for it.

[walfie]

Another workaround is to have the CLI tool write a batch script that has the appropriate stop/start commands, and then execute that instead, but it feels very hacky