Fix three bugs: 1. Hudi slice maybe has log files only, so `new Path(filePath)` will throw errors. 2. Hive column names are lowercase only, so match column names in ignore-case-mode. 3. Compatible with [Spark Datasource Configs](https://hudi.apache.org/docs/configurations/#Read-Options), so users can add `hoodie.datasource.merge.type=skip_merge` in catalog properties to skip merge logs files.