feat: introduce Buffer for non-continuous bytes (#5164)

* feat: introduce Buffer for non-continuous bytes

* Update src/mito2/src/cache/index.rs

Co-authored-by: Weny Xu <wenymedia@gmail.com>

* chore: apply review comments

* refactor: use opendal::Buffer

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Co-authored-by: Weny Xu <wenymedia@gmail.com>

src/common/base/Cargo.toml

@@ -17,6 +17,7 @@ common-macro.workspace = true
 futures.workspace = true
 paste = "1.0"
 pin-project.workspace = true
+rand.workspace = true
 serde = { version = "1.0", features = ["derive"] }
 snafu.workspace = true
 tokio.workspace = true