ProtoEnv: remove `protocol.mli` and `tezos_data.mli` (fix #2897)
This is following !4961 (merged) and a fix for #2897 (closed) @raphael-proust @mbouaziz
Edited by Mehdi Bouaziz
This is following !4961 (merged) and a fix for #2897 (closed) @raphael-proust @mbouaziz