Improve on the hardcoded PICO_SDK_PATH in Firmware/LogicAnalyzer CMakeLists.txt

[Ragebone]

Hello, current version in the master hardcodes the SDK path, link here: https://github.com/gusmanb/logicanalyzer/blob/6ab103e120eba0f76b678651ea4dabeb6a76e063/Firmware/LogicAnalyzer/CMakeLists.txt#L10

The included pico_sdk_import.cmake can handle taking PICO_SDK_PATH from the environment but won't because it is already defined.

Please excuse me asking like this, is it possible for you to use the environment variable for setting the SDK-Path instead?

Thank you. Sincerely Norman