checkin initial MVCC codebase

Signed-off-by: Alex Chi <iskyzh@gmail.com>

mini-lsm-mvcc/src/bin/compaction-simulator.rs

@@ -0,0 +1 @@
+../../../mini-lsm-starter/src/bin/compaction-simulator.rs

mini-lsm-mvcc/src/bin/mini-lsm-cli.rs

@@ -0,0 +1 @@
+../../../mini-lsm-starter/src/bin/mini-lsm-cli.rs

mini-lsm-mvcc/src/bin/wrapper.rs

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+pub mod mini_lsm_wrapper {
+    pub use mini_lsm_mvcc::*;
+}
+
+#[allow(dead_code)]
+fn main() {}