Feature/file storage: Binary File Create/Append

[tom6311tom6311]

Brief

• Implement binary file creation and append functionalities
• Implement conversion from attribute value to byte vector and vice versa

Features:

1. Add attr_offset_ranges to TableMeta struct, which specifies the [start, end] index of each attribute value of each row stored in the binary file.
2. Modify File::create_table, File::drop_table, File::append_rows to support table and row level operations on binary files.
3. Implement BytesCoder to perform conversion between attributes value and byte vectors
   • BytesCoder::from_bytes converts a byte vector to string value of specified datatype
   • BytesCoder::to_bytes converts a string value of specified datatype to a byte vector
4. Design test cases for the functionalities above.