Add tasks for all the new languages

Task/Call-a-function/Swift/call-a-function.swift

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+// call a function with no args
+noArgs()
+
+// call a function with one arg with no external name
+oneArgUnnamed(1)
+
+// call a function with one arg with external name
+oneArgNamed(arg: 1)
+
+// call a function with two args with no external names
+twoArgsUnnamed(1, 2)
+
+// call a function with two args and external names
+twoArgsNamed(arg1: 1, arg2: 2)
+
+// call a function with an optional arg
+// with arg
+optionalArguments(arg: 1)
+// without
+optionalArguments() // defaults to 0
+
+// function that takes another function as arg
+funcArg(noArgs)
+
+// variadic function
+variadic(opts: "foo", "bar")
+
+// getting a return value
+let foo = returnString()
+
+// getting a bunch of return values
+let (foo, bar, baz) = returnSomeValues()
+
+// getting a bunch of return values, discarding second returned value
+let (foo, _, baz) = returnSomeValues()