*: replace interface{} with any keyword

Everywhere including examples, external interop APIs, bindings generators
code and in other valuable places. A couple of `interface{}` usages are
intentionally left in the CHANGELOG.md, documentation and tests.

pkg/compiler/nilcheck_test.go

@@ -11,7 +11,7 @@ var nilTestCases = []testCase{
 		`
 		package foo
 		func Main() int {
-			var t interface{}
+			var t any
 			if t == nil {
 				return 1
 			}
@@ -39,7 +39,7 @@ var nilTestCases = []testCase{
 		`
 		package foo
 		func Main() int {
-			var t interface{}
+			var t any
 			if nil == t {
 				return 1
 			}