gRPC-Core Release 1.70.0

[stanle...@google.com]

This is 1.70.0 (genius) release announcement for gRPC-Core and the wrapped languages C++, C#, Objective-C, Python, PHP and Ruby. Latest release notes are here.

This release contains refinements, improvements, and bug fixes, with highlights listed below.

Core

• [BoringSSL] Update third_party/boringssl-with-bazel. (#38274)

C++

• gRPC C++ begins to require C++17 or later to build and use gRPC C++. You may need the following settings
• CMake: Add CMAKE_CXX_STANDARD=17 to your CMake build command.
• Bazel: Add --cxxopt='/std:c++17' and --host_cxxopt='/std:c++17' to your Bazel build command.
• gRPC 1.69, the final version compatible with C++14, will be supported until December 10, 2025, according to https://github.com/grpc/proposal/blob/master/L120-requiring-cpp17.md.