Better better autogen

[ShiCheng-Lu]

Um, so this needs scons 4.x, which is installed via pip instead of apt. scons 3.6 uses outdated version of python (or maybe python2 instead of python3)
pip install scons

Test plan:

none platform specific:

• format + lint
• new project/smoke/task/lib/py

x86:

• build
• test + clean test
• rebuild when project change
• re-autogen when autogen or config change
• sim + clean sim
• build python runs python
• gdb + clean gdb

arm:

• build
• test + clean test
• rebuild when project change
• re-autogen when autogen or config change
• flash + clean flash
• mem-report

[ShiCheng-Lu]

tests runs too slow on x86 lmao,