compiler: fix difference in aliases in interface methods

There used to be a difference between `byte` and `uint8` in interface
methods. These are aliases, so they should be treated the same.
This patch introduces a custom serialization format for types,
circumventing the `Type.String()` method that is slightly wrong for our
purposes.

This also fixes an issue with the `any` keyword in Go 1.18, which
suffers from the same problem (but this time actually leads to a crash).

testdata/interface.go

@@ -40,6 +40,9 @@ func main() {
 	// https://github.com/tinygo-org/tinygo/issues/453
 	_, _ = itf.(Empty)
 
+	var v Byter = FooByte(3)
+	println("Byte(): ", v.Byte())
+
 	var n int
 	var f float32
 	var interfaceEqualTests = []struct {
@@ -266,3 +269,11 @@ type StaticBlocker interface {
 }
 
 type Empty interface{}
+
+type FooByte int
+
+func (f FooByte) Byte() byte { return byte(f) }
+
+type Byter interface {
+	Byte() uint8
+}

testdata/interface.txt

@@ -20,6 +20,7 @@ Stringer.String(): foo
 Stringer.(*Thing).String(): foo
 s has String() method: foo
 nested switch: true
+Byte():  3
 non-blocking call on sometimes-blocking interface
 slept 1ms
 slept 1ms