* initial version for 3fs native api
* delete redundant code in file_interface and storage_backend. Only keep api in use
* refactor some problem
* refactor file interface, add lockRAII
* fix some problem
* fix test problem
* rm char file interface , edit filemode
* edit cmake file , mkdir hf3fs in store
* Refactor 3FS plugin integration: break circular includes, rename symbols for clarity, and ensure StorageFile is fully visible before ThreeFSFile inherits it.
* add span<char> writefile interface
* restore puttolocalfile
* add document for 3fs usage guide
* add tl::expected<> return type, add use_3fs macro in code
* fix test fail
* add check read/write size equals to length
* fix test
doujiang24