## Rationale
In current design, sst files may be picked multiple times.

## Detailed Changes
- Mark files as in compacting when pick files candidates, and reset it
to false when CompactionTask is dropped.

## Test Plan
Manually

## Rationale
The metadata for arrow schema is encoded into the parquet file. However,
this part is lost when building our custom metadata.

## Detailed Changes
Keep the other metadata in the parquet metadata after extracting our
custom metadata.

## Test Plan
Add unit test `test_arrow_meta_data` for it.

## Rationale
Part of apache#990.

Some background jobs are still allowed to execute, and it will lead to
data corrupted when a table is migrated between different nodes because
of multiple writers for the same table.

## Detailed Changes
Introduce a flag called `invalid` in the table data to denote whether
the serial executor is valid, and this flag is protected with the
`TableOpSerialExecutor` in table data, and the `TableOpSerialExecutor`
won't be acquired if the flag is set, that is to say, any table
operation including updating manifest, altering table and so on, can't
be executed after the flag is set because these operations require the
`TableOpSerialExecutor`. Finally, the flag will be set when the table is
closed.

…eresdb into fix-page-index-for-metadata