[Android] Add script to install protoc for CI

Summary:
Add protobuf install script to make installation of the protoc
command easy for CI.

The intent is to use a more recent version of protobuf which doesn't fail
immediately when "optional" is present in a protobuf file. Ubuntu still uses
3.12 which deprecated optional, but 3.15 added usage of optional back.

https://linear.app/comm/issue/ENG-2404

Test Plan:

$ docker run -it --rm -v $PWD:/comm reactnativecommunity/react-native-android:latest /bin/bash

# apt update
# apt install -y autoconf libtool build-essential cmake git libgtest-dev libssl-dev zlib1g-dev
# ./comm/native/android/scripts/install_protobuf.sh
# protoc --version
libprotoc 3.15.8

Example run (just asserts that protobuf was installed correctly, not that it was used):
https://buildkite.com/comm/android-ci-plus-protoc-install/builds/1#01850bfd-2572-4257-b2fe-afbd13f48d04

Reviewers: atul, max, varun

Reviewed By: max

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D5861