Fix ESP-IDF environment activation

[SergioGasquez]

• Update embuild version to be at least 0.28.5
• Update esp-idf-sys version to be at least 0.31.5
• Update embeded-sv version to be at least 0.19
• Clear unnecesary environment variables
• Add sourcing esp-idf export script and IDF_TOOLS_PATH environment variable
• CMake is now installed via idf_tools.py (it installs the proper version for ESP-IDF)

[justahero]

Hello @SergioGasquez ,

thanks for your contribution. 👍

Please note that #70 was merged earlier, which results in a merge conflict now. That PR fixes the Github CI workflow & reduces the resulting image size slightly. Unfortunately it also required some changes to the Dockerfile to play well with Github Actions. The Docker image can now be used by the Github CI workflow & as a VS Code devcontainer.

If you want, I can resolve the merge conflict. Once done the new CI job should then trigger automatically to test the dependencies changes within the Docker image. Please don't hesitate if you see something wrong or have suggestions how to further reduce the image size. The final image sits currently at ~3.0Gb.

[SergioGasquez]

Hi @justahero! Just resolved the conflicts, please, have a look at them and let me know if you think there is anything we can improve!