caseSensitive option.

## Proposed change

The example in [README.md](https://github.com/embulk/embulk-filter-calcite) needs to fix
Because this example use lowercase column name.
Calcite converts lowercase column name to uppercase by default.
So, this example raises error like below until set `caseSensitive: false` option.

Reported by [joker](https://twitter.com/joker1007/status/1298279433879449600?s=20) in Twitter

## Reproduce steps.

```
embulk example hoge
embulk guess hoge/seed.yml -o config.yml
```

Add the following filter rule. this config used in the README example.

```yaml
filters:
- type: calcite
query: SELECT * FROM $PAGES WHERE id IN (1, 2)
```

```
embulk preview config.yml
```

## Error

```
org.embulk.config.ConfigException: Cannot execute a query: SELECT * FROM $PAGES WHERE id IN (1, 2)
at org.embulk.filter.calcite.CalciteFilterPlugin.executeQuery(CalciteFilterPlugin.java:178)
at org.embulk.filter.calcite.CalciteFilterPlugin.getQuerySchema(CalciteFilterPlugin.java:150)
at org.embulk.filter.calcite.CalciteFilterPlugin.transaction(CalciteFilterPlugin.java:72)
at org.embulk.spi.util.Filters$RecursiveControl.transaction(Filters.java:76)
at org.embulk.spi.util.Filters.transaction(Filters.java:42)
at org.embulk.exec.PreviewExecutor$2.run(PreviewExecutor.java:112)
at org.embulk.spi.FileInputRunner$RunnerControl$1$1.run(FileInputRunner.java:112)
at org.embulk.standards.CsvParserPlugin.transaction(CsvParserPlugin.java:237)
at org.embulk.spi.FileInputRunner$RunnerControl$1.run(FileInputRunner.java:107)
at org.embulk.spi.util.Decoders$RecursiveControl.transaction(Decoders.java:68)
at org.embulk.spi.util.Decoders$RecursiveControl$1.run(Decoders.java:64)
at org.embulk.standards.GzipFileDecoderPlugin.transaction(GzipFileDecoderPlugin.java:25)
at org.embulk.spi.util.Decoders$RecursiveControl.transaction(Decoders.java:60)
at org.embulk.spi.util.Decoders.transaction(Decoders.java:29)
at org.embulk.spi.FileInputRunner$RunnerControl.run(FileInputRunner.java:105)
at org.embulk.exec.BufferFileInputPlugin.transaction(BufferFileInputPlugin.java:21)
at org.embulk.spi.FileInputRunner.transaction(FileInputRunner.java:62)
at org.embulk.exec.PreviewExecutor.doPreview(PreviewExecutor.java:110)
at org.embulk.exec.PreviewExecutor.doPreview(PreviewExecutor.java:96)
at org.embulk.exec.PreviewExecutor.access$000(PreviewExecutor.java:28)
at org.embulk.exec.PreviewExecutor$1.run(PreviewExecutor.java:65)
at org.embulk.exec.PreviewExecutor$1.run(PreviewExecutor.java:62)
at org.embulk.spi.Exec.doWith(Exec.java:22)
```