do not allow upgrade node if clang version is < 16

[yungwine]

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Pull Request Overview

This PR prevents the node upgrade from proceeding if the installed clang version is lower than 16. Key changes include:

• Adding a clang version check in the Upgrade function.
• Introducing a helper function (get_clang_major_version) to extract the clang major version.

Comments suppressed due to low confidence (1)

mytonctrl/mytonctrl.py:373

• [nitpick] For improved readability of the error output, consider appending an explicit newline character after the instructions URL so that the message isn't concatenated onto the end of the URL.

			text += "Could not check clang version.\n If you are sure that clang version is 16 or higher, use --force option.\n"