Please publish santised Dockerfiles used for CI

#### Describe your problem or use case <!-- A clear and concise description of what the problem is and what you are trying to accomplish. --> I want to be able to build realm-core locally, especially packaging it for Android. I think this is going to be needed to support 16KB page sizes (which is mandatory by Nov 1st 2025). With Mongo deprecating and, shortly, EOLing the Realm SDKs it looks like the community is going to have to do this. Currently I've been struggling to setup an environment locally that can use `tools/cross-compile.sh` to build the current state of the project and the devcontainers setup is reliant on private docker images. #### Describe the solution you'd like <!-- A clear and concise description of how you think a solution could look like. --> It looks like there are various Dockerfiles (`android.Dockerfile`, etc) used in the private CI process to build, test and package Realm (. These used to be in the repo directly but were moved to a private one under PR #5327 Could the Mongo devs please sanitize (e.g. drop anything that shouldn't be revealed publicly) and publish the Dockerfiles back into the repo for community use? #### Additional context <!-- Add any other context about the feature request here. --> https://github.com/realm/realm-js/issues/7015 https://developer.android.com/guide/practices/page-sizes