container + config for VSCode

[rrbutani]

.devcontainer config file w/gdb and friends (docker, clangd) + build tasks for all the ninja things + Dockerfile that uses this as a base + adds git and ip and ifconfig

if we're being really fancy, a function to get debug and release mode
or just separate tasks for each

tricky bit is a new debug script (like the lldb script) that kicks up an openocd server with a TCP connection and then starts gdb with the right flags. Call it gdb-mi or something

it'll share a lot with the lldb script but I don't think it's worth refactoring yet

[rrbutani]

oh, also add the debug config of course