Is there an existing issue for the same feature request?

• I have checked the existing issues.

Is your feature request related to a problem?

Unnecessary data copy from `ColumnBuffer` to `ColumnVector`

Describe the feature you'd like

Read from file to ColumnVector
Remove ColumnBuffer.

1. Add interface GetColumnVector in BlockColumnEntry, which load the column of entry from disk. The data lifetime of returned column vector is managed by buffer_manager.
2. Varchar type use FixHeapManager to allocate and read/load chunk. One chunk is mapped to one outline file on disk.

Describe implementation you've considered

No response

Documentation, adoption, use case

No response

Additional information

No response