Replace some FIR syntax errors with more proper diagnostics

compiler/testData/diagnostics/tests/controlStructures/ForbidStatementAsDirectFunctionBody.fir.kt

@@ -1,5 +1,5 @@
 
-fun foo1() = while (b()) {}
+fun foo1() = <!EXPRESSION_REQUIRED!>while (b()) {}<!>
 
 fun foo2() = <!UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE!>for (i in 10) {}<!>
 

compiler/testData/diagnostics/tests/controlStructures/continueAndBreakLabelWithSameFunctionName.fir.kt

@@ -19,7 +19,7 @@ class Test3 {
 }
 
 fun test4() {
-    break@test4
+    <!BREAK_OR_CONTINUE_OUTSIDE_A_LOOP!>break@test4<!>
 }
 
 class Test5 {
@@ -43,11 +43,11 @@ class Test6 {
 class Test7 {
     fun Test7() {
         Test8@ while (true) {
-            break@Test7
+            <!NOT_A_LOOP_LABEL!>break@Test7<!>
         }
 
         Test7@ while (true) {
-            break@Test8
+            <!NOT_A_LOOP_LABEL!>break@Test8<!>
         }
     }
 }

compiler/testData/diagnostics/tests/controlStructures/kt770.fir.kt351.fir.kt735_StatementType.fir.kt

@@ -15,7 +15,7 @@ fun main() {
 }
 
 //KT-351 Distinguish statement and expression positions
-val w = while (true) {}
+val w = <!EXPRESSION_REQUIRED!>while (true) {}<!>
 
 fun foo() {
     var z = 2
@@ -152,12 +152,12 @@ fun bar(a: Unit) {}
 
 fun testStatementInExpressionContext() {
     var z = 34
-    val a1: Unit = z = 334
+    val a1: Unit = <!EXPRESSION_REQUIRED!>z = 334<!>
     val f = for (i in 1..10) {}
-    if (true) return z = 34
-    return while (true) {}
+    if (true) return <!EXPRESSION_REQUIRED!>z = 34<!>
+    return <!EXPRESSION_REQUIRED!>while (true) {}<!>
 }
 
 fun testStatementInExpressionContext2() {
-    val a2: Unit = while(true) {}
+    val a2: Unit = <!EXPRESSION_REQUIRED!>while(true) {}<!>
 }