[BUG] string(bool) overload is missing

--- name: Bug report about: Create a report to help us improve --- **Describe the bug** When trying to run string(bool) in cel-java a CelValidationException for overload not found. **To Reproduce** Check which components this affects: - [ ] parser - [x] checker - [x] runtime Sample expression and input that reproduces the issue: ```cel string(true) ``` **Expected behavior** CEL should compile and run resulting a string.