refactor(core): MaybeSend does not need to be unsafe #8024

Job	Run time
build-java-doc	24s
build-nodejs-doc	19s
build-python-doc	3m 4s
build-rust-doc	4m 22s
build-c-doc	26s
build-haskell-doc	3m 14s
build-lua-doc	8s
build-cpp-doc	25s
build-dav-server-opendalfs-doc	45s
build-fuse3-opendal-doc	42s
build-object-store-opendal-doc	57s
build-ocaml-doc	4m 59s
build-unftp-sbe-opendal-doc	1m 15s
build-opendal-compat-doc	42s
build-virtiofs-opendal-doc	55s
build-parquet-opendal-doc	49s
build-website	3m 18s
	26m 44s

Provide feedback