tfdbg: add "print_source" ("ps") command to profiler mode

Related changes:
* Refactored part of cli/profile_analyzer_cli.py to new file lib/profiling.py.
* Improve the way in which filtering is done for file path and line number.
* Add unit test for the "lp" and "ps" commands under tf.while_loops.
* Add op type to the "lp" table. Also add the ability to sort the rows by op type.
* Let the length of the all-"-" divider scale automatically with screen with in the curses UI.

PiperOrigin-RevId: 156502357