Fix hang when returning from shell command

In 5a3049485c we changed the execution of shell commands to use an interactive
shell (-i), because this allows users to use aliases or shell functions, which
is a nice convenience.

Since then, however, many users have reported problems with lazygit not coming
back to the foreground after executing a shell command. Some users report that
appending "; exit" to the end of the command line solves this. I don't really
understand what the cause of this problem was, or why appending "; exit" solves
it, but if it helps, let's do it.

pkg/commands/oscommands/cmd_obj_builder.go

@@ -52,7 +52,7 @@ func (self *CmdObjBuilder) NewShell(commandStr string) ICmdObj {
 }
 
 func (self *CmdObjBuilder) NewInteractiveShell(commandStr string) ICmdObj {
-	quotedCommand := self.quotedCommandString(commandStr)
+	quotedCommand := self.quotedCommandString(commandStr + self.platform.InteractiveShellExit)
 	cmdArgs := str.ToArgv(fmt.Sprintf("%s %s %s %s", self.platform.InteractiveShell, self.platform.InteractiveShellArg, self.platform.ShellArg, quotedCommand))
 
 	return self.New(cmdArgs)

pkg/commands/oscommands/dummies.go

@@ -56,6 +56,7 @@ var dummyPlatform = &Platform{
 	InteractiveShell:     "bash",
 	ShellArg:             "-c",
 	InteractiveShellArg:  "-i",
+	InteractiveShellExit: "; exit $?",
 	OpenCommand:          "open {{filename}}",
 	OpenLinkCommand:      "open {{link}}",
 }

pkg/commands/oscommands/os.go

@@ -40,6 +40,7 @@ type Platform struct {
 	InteractiveShell     string
 	ShellArg             string
 	InteractiveShellArg  string
+	InteractiveShellExit string
 	OpenCommand          string
 	OpenLinkCommand      string
 }

pkg/commands/oscommands/os_default_platform.go

@@ -15,6 +15,7 @@ func GetPlatform() *Platform {
 		InteractiveShell:     getUserShell(),
 		ShellArg:             "-c",
 		InteractiveShellArg:  "-i",
+		InteractiveShellExit: "; exit $?",
 		OpenCommand:          "open {{filename}}",
 		OpenLinkCommand:      "open {{link}}",
 	}

pkg/commands/oscommands/os_windows.go

@@ -7,5 +7,6 @@ func GetPlatform() *Platform {
 		InteractiveShell:     "cmd",
 		ShellArg:             "/c",
 		InteractiveShellArg:  "",
+		InteractiveShellExit: "",
 	}
 }