ci: Add ios jobs

## Context
following PR #196 we should be able to have an iOS workflow using the ios SDK provided in the macos-11 virtual-environments.

* [ ] Add new workflows: `aarch64_ios.yml` and `arm_ios.yml`
* [ ] Update Matrix in ci/README.md by adding the new badges

## Biblio

* CMake ios SDK usage doc
https://cmake.org/cmake/help/latest/manual/cmake-toolchains.7.html#cross-compiling-for-ios-tvos-or-watchos

* Installed SDK in macos-11 images: https://github.com/actions/virtual-environments/blob/main/images/macos/macos-11-Readme.md#installed-sdks