Unsupported expressions found in spark sql unit test

### What is the problem the feature request solves?

Some unsupported expressions found in spark sql unit test:
- [ ] `Abs`: Duplicate of https://github.com/apache/datafusion-comet/issues/1890
- [ ] `Base64`
- [ ] `CheckOverflowInTableInsert`
- [ ] `Concat` #2604
- [ ] `DayOfMonth` | `Month`: https://github.com/apache/datafusion-comet/issues/2315
- [ ] `DenseRank`
- [ ] `Empty2Null`
- [ ] `ElementAt`: because: Input is not an array, refer to datafusion [map_extract](https://datafusion.apache.org/user-guide/sql/scalar_functions.html#map-extract)
- [ ] `FormatString`
- [ ] `Greatest`: https://datafusion.apache.org/user-guide/sql/scalar_functions.html#greatest
- [ ] `Literal`: Comet cannot accelerate Literal because: Unsupported datatype ArrayType(LongType,true), refer to https://github.com/apache/datafusion-comet/pull/2057
- [ ] `NaNvl`: refer to datafusion [nanvl](https://datafusion.apache.org/user-guide/sql/scalar_functions.html#nanvl)
- [ ] `Pmod`
- [ ] `RowNumber`
- [ ] `Size`
- [ ] `StringSplit`
- [ ] `TimeAdd`
- [ ] `ToCharacter`
- [ ] `WidthBucket`: Implementation in datafusion-spark https://github.com/apache/datafusion/pull/17331

### Describe the potential solution

_No response_

### Additional context

_No response_