[TD] Update diagnostics test data due to new test runners

Update includes:
- Changing syntax of `OI/`NI` tags from `<!NI;TAG!>` to `<!TAG{NI}!>`
- Fix some incorrect directives
- Change order of diagnostics in some places
- Remove ignored diagnostics from FIR test data (previously `DIAGNOSTICS` didn't work)
- Update FIR dumps in some places and add `FIR_IDENTICAL` if needed
- Replace all JAVAC_SKIP with SKIP_JAVAC directive

compiler/testData/diagnostics/tests/smartCasts/varnotnull/varNull.kt

@@ -2,5 +2,5 @@
 fun foo(): Int {
     var s: String? = <!VARIABLE_WITH_REDUNDANT_INITIALIZER!>"abc"<!>
     s = null
-    return <!OI;DEBUG_INFO_CONSTANT!>s<!><!UNSAFE_CALL!>.<!>length
-}
+    return <!DEBUG_INFO_CONSTANT{OI}!>s<!><!UNSAFE_CALL!>.<!>length
+}