[clang] [llvm] [AVR] Add many new AVR MCU model definitions (PR #144229)

[Tom Vijlbrief via llvm-commits]

tomtor wrote:

Double checking https://onlinedocs.microchip.com/oxy/GUID-0B644D8F-67E7-49E6-82C9-1B2B9ABE6A0D-en-US-23/GUID-33953345-30E8-49BC-89A0-9734DC6EA5B9.html

https://github.com/llvm/llvm-project/pull/144229