Generate a separate test method for each operator.

This way the test result report is more useful, since we see the status
of each operator separately rather than all wrapped up in one. This is
particularly important when there are failures, because then having them
all in one function causes the first failure to mask the others.
Enumerate all of the binary operators to test, commented out.

This is in preparation for implementing them, as a note-to-self about the
expected precedence order.
Stick to the _expression suffix even for the generated test methods.
Parse the comparison operators.
Parse bitwise "and" and "or".
Parse the left and right shift operators.
Parse the binary arithmetic operators.