Currently, Doris has a variety of readers for different file formats,
such as parquet reader, orc reader, csv reader, json reader and so on.
The interfaces of these readers are not unified, which makes it impossible to call them through a unified method.
In this PR, I added a `GenericReader` interface class, and other Readers will implement this interface class
to use the `get_next_block()` method.
This PR currently only modifies `arrow_reader` and `parquet reader`.
Other readers will be modified one by one in subsequent PRs.
There is two issue fixed in this pr:
**The first issue** is the C++ code rule of `do not call virtual function in constructor or deconstructor`.
The deconstructor function of `ArrowReaderWrap` call the virtual function named `close()`.
When deconstructing, it will never call `ParquetReaderWrap::close()` just call the `ArrowReaderWrap::close()`
**The second issue** is parallelism deconstructing for `ParquetReaderWrap` and `prefetch_batch`.
`prefetch_batch` use `thread.detach()` to separate the control from `ParquetReaderWrap`, but it rely on some local vars from `ParquetReaderWrap` such as **`_closed ` /`_total_groups ` and `_reader`**
In this case, `ParquetReaderWrap` may call deconstructor before `prefetch_batch` and then get the core dump.
Only support one level array now.
for example:
- nullable(array(nullable(tinyint))) is **support**.
- nullable(array(nullable(array(xx))) is **not support**.
