tests/lx: Make lexer line/col/byte tests more specific.
tests/lx: Make lexer line/col/byte tests more specific.

Note: these tests are currently failing.

- Make each token in the sample data check the start and end for the
  line, column, and byte offset. This caught an issue with how `end.col`
  is handled around line breaks that aren't at the end of the input
  string.

- Add a case after the line comment, which found that the current
  generated lexer isn't exiting the until-end-of-line comment zone
  at the line break.

katef/libfsm,katef/libfsm,katef/libfsm,katef/libfsm,katef/libfsm