Fix the handling of paste.

Author: knz

driver.go

@@ -462,8 +462,8 @@ func (d *driver) ApplyTextCommand(t TB, cmd string, args ...string) tea.Cmd {
 		d.addMsg(tea.KeyMsg(tea.Key{Type: tea.KeyEnter}))
 
 	case "paste":
-		d.assertArgc(t, args, 1)
-		s, err := strconv.Unquote(args[0])
+		arg := strings.Join(args, " ")
+		s, err := strconv.Unquote(arg)
 		if err != nil {
 			t.Fatalf("%s: paste argment error: %v", d.pos, err)
 		}

testdata/simple

@@ -74,17 +74,17 @@ TEA PRINT: {MODEL UPDATE}
 MODEL VIEW🛇
 
 run trace=on
-paste "ab\ncd"
+paste "a b\nc d"
 ----
--- trace: before "paste \"ab\\ncd\""
+-- trace: before "paste \"a b\\nc d\""
 -- trace: after "paste"
 -- view:
 MODEL VIEW🛇
 -- trace: before finish
 -- view:
 MODEL VIEW🛇
 -- trace: processing 1 messages
--- trace: msg tea.KeyMsg{Type:-1, Runes:[]int32{97, 98, 10, 99, 100}, Alt:false}
+-- trace: msg tea.KeyMsg{Type:-1, Runes:[]int32{97, 32, 98, 10, 99, 32, 100}, Alt:false}
 -- trace: processing 1 cmds
 -- trace: translated cmd: tea.printLineMessage
 -- trace: processing 1 messages