[lldb-dap] Fix running dap_server.py directly for debugging tests.

This adjusts the behavior of running dap_server.py directly to better support the current state of development.

* Instead of the custom tracefile parsing logic, I adjusted the replay helper to handle parsing lldb-dap log files created with the `LLDBDAP_LOG` env variable.
* Migrated argument parsing to `argparse`, that is in all verisons of py3+ and has a few improvements over `optparse`.
* Corrected the existing arguments and updated `run_vscode` > `run_adapter`. You can use this for simple debugging like: `xcrun python3 lldb/packages/Python/lldbsuite/test/tools/lldb-dap/dap_server.py --adapter=lldb-dap --adapter-arg='--pre-init-command' --adapter-arg 'help' --program a.out --init-command 'help'`

Author: ashgti