In some cases we transform flexible type into non-flexible during
enhancement, but don't add `@EnhancedNullability` attribute to them,
which breaks consistency with K1 on IR level
This commit fixes it
^KT-65302
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