[rust] Remove protoc build time dependency from users

[kvcache]

Installing protoc is a pain this library unnecessarily pushes onto users. We should instead check in generated protos such that the momento library does not have a custom build.rs invoking protoc.

Here is an example of a library that has an unpublished workspace member project that only generates protos into its main published library project: https://github.com/kvc0/goodmetrics_rs
It handles catching missed definition updates at PR time, and again at release time (because it does not allow a locally dirty repo, which it is very right to prohibit and we should do that here too).

We have many downstream examples of the impact of this missing support, both in the SDK and transitively in the CLI. All users will also need to install it to use momento today.

To complete this issue, end users must be able to declare a momento dependency without also installing protoc. Only developers of this project (and github) will need to install protoc. We will be able to remove the install_protoc.sh scripts from the SDK as well as the CLI, simplifying our own build pipelines as well.