GDScript: Fix await type inference

modules/gdscript/tests/scripts/analyzer/errors/await_signal_no_infer.gd

@@ -0,0 +1,4 @@
+signal my_signal()
+
+func test():
+	var _a := await my_signal

modules/gdscript/tests/scripts/analyzer/errors/await_signal_no_infer.out

@@ -0,0 +1,2 @@
+GDTEST_ANALYZER_ERROR
+Cannot infer the type of "_a" variable because the value doesn't have a set type.

modules/gdscript/tests/scripts/analyzer/features/await_type_inference.gd

@@ -0,0 +1,15 @@
+func coroutine() -> int:
+	@warning_ignore("redundant_await")
+	await 0
+	return 1
+
+func not_coroutine() -> int:
+	return 2
+
+func test():
+	var a := await coroutine()
+	@warning_ignore("redundant_await")
+	var b := await not_coroutine()
+	@warning_ignore("redundant_await")
+	var c := await 3
+	prints(a, b, c)

modules/gdscript/tests/scripts/analyzer/features/await_type_inference.out

@@ -0,0 +1,2 @@
+GDTEST_OK
+1 2 3