This adds the Python files in the tests/ directory to be formatted with
./tools/codeformat.py. The basics/ subdirectory is excluded for now so we
aren't changing too much at once.
In a few places `# fmt: off`/`# fmt: on` was used where the code had
special formatting for readability or where the test was actually testing
the specific formatting.
In strict stackless mode, it's not possible to make a function call with
heap locked (because function activation record aka frame is allocated on
heap). So, if the only purpose of function is to introduce local variable
scope, move heap lock/unlock calls inside the function.