Add --config to use customize configuration file

**Is your feature request related to a problem? Please describe.**
No

**Describe the solution you'd like**

```bash
$ pudb3 --help
usage: pudb3 [options] [-m] SCRIPT-OR-MODULE-TO-RUN [SCRIPT_ARGS]

positional arguments:
script_args Arguments to pass to script or module

optional arguments:
-h, --help show this help message and exit
-s, --steal-output
-m, --module Debug as module or package instead of as a script
-le FILE, --log-errors FILE
Log internal errors to the given file
--pre-run COMMAND Run command before each program run
--config CONFIG Use config file [Default: ~/.config/pudb/pudb.cfg]
--version show program's version number and exit

pudb:pudb3 v2022.1.2
```