[Wasm] stdlib API: make kotlin.assert internal

Being disabled by default
 and not well-documented, these functions cause confusion among early
 adopters as to why their code don't work properly.

Assert APIs need a proper design across Kotlin platforms.
 Since APIs are not available in common code and K/JS, it is premature
  to have such a general feature in a new experimental platform.

Compiler tests:
* Mute tests that rely on assert.
* Replace JVM-specific assert calls with require calls and unmute passed K/JS tests.

Merge-request: KT-MR-8636
Merged-by: Svyatoslav Kuzmich <svyatoslav.kuzmich@jetbrains.com>

compiler/testData/codegen/box/casts/functions/isFunKBig.kt

@@ -40,11 +40,11 @@ abstract class TestFnBase(val type: String) {
     abstract fun testBad(x: Any)
 
     protected fun assertIs(x: Any, condition: Boolean) {
-        assert(condition) { "x is $type: failed for $x" }
+        require(condition) { "x is $type: failed for $x" }
     }
     
     protected fun assertIsNot(x: Any, condition: Boolean) {
-        assert(condition) { "x !is $type: failed for $x" }
+        require(condition) { "x !is $type: failed for $x" }
     }
 }