Mbed Update to v5.15.1

[ivankravets]

Sorry for the delay

Support for Mbed OS 6: Stable and mature APIs, Cloud services support, Enhancements to the Bare Metal Profile

[mbedos-logo] We’re happy to announce updated support for the new Mbed OS 6 - a free, open-source embedded operating system designed specifically for the low-powered, constrained and connected devices. Besides many great improvements, security updates, and bug fixes, Mbed OS 6 also brings a lot of breaking changes. Mbed OS 6 removes a great deal of deprecated functionality, heavily reduces the list of supported boards and platforms, only officially supported and well-maintained targets are le…