Fix the bug that Upgrading from rocksdb-4.13 to rocksdb-6.12.6 failed…(#10)

[lylth]

… initialization

Fix the bug that the initialization failed when upgrading from rocksdb-4.13 to rocksdb-6.12.6...(#10)
During initialization, the MANIFEST file of rocksdb is checked to obtain the column family name, but the CURENT file that stores the MANIFEST log in the initial state does not exist, and the error code of IOERROR is returned. The corresponding subcode of IOERROR returned by rocksdb4.13 is kNone, rocksdb6.4.6 Version IOERROR adds a subcode of kPathNotFound.
Stonedb judged that there is only kNone, so it did not go through the process of creating the default column family, resulting in "Default column family not specified" and subsequent errors. Add the "rocksdb::Status::kPathNotFound" judgment process of subcode to create a default column family file to solve the problem of initialization failure

Summary about this PR

Issue Number: close #10

Tests Check List

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Changelog

• New Feature
• Bug Fix
• Improvement
• Performance Improvement
• Build/Testing/CI/CD
• Documentation
• Not for changelog (changelog entry is not required)

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features