Move OpenSSL < 3.0 compatibility stub to azure-c-shared-utility

[ewertons]

Problem

Currently, the Azure IoT SDK-C maintains a compatibility stub for OpenSSL < 3.0 in the SDK itself (see PR #2724):

• File: \compat_stubs/csr_gen_openssl_stub.c\
• Linked from: \CMakeLists.txt\ (line ~395)

This stub is needed because \EVP_EC_gen()\ was added in OpenSSL 3.0, which affects cross-compile environments (ARM/MIPS Docker images) still using OpenSSL 1.0.2 or 1.1.1.

Root Cause

The actual implementation (\csr_gen_openssl.c) already exists in azure-c-shared-utility (upstream dependency). The stub should be part of that library, not duplicated in this SDK.

Expected Work

1. Move \compat_stubs/csr_gen_openssl_stub.c\ to \�dapters/\ in azure-c-shared-utility
2. Update azure-c-shared-utility's CMakeLists.txt to conditionally use the stub when \OPENSSL_VERSION_NUMBER < 0x30000000L\
3. Remove the stub and conditional compilation from azure-iot-sdk-c CMakeLists.txt (line ~390-404)
4. Update azure-iot-sdk-c's dependency on azure-c-shared-utility to point to the version containing the fix

Related PR

See: https://github.com/Azure/azure-iot-sdk-c/pull/2724/files