pw_console: Urwid implementation

Copy of https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/25643/

- General UI Fixes
  - DONE: fix search by making a LogLine container class
  - DONE: fix log line scrolling
  - DONE: move to pw_console
  - DONE: load settings (keybinds/colorscheme) from //.pw_ide.conf file
  - DONE: log line mouse scroll/click
  - toggle vertical/horizonal split
  - split resizing (with mouse?)
  - convert help pane to overlay
  - add keybind to allow focus to leave ipython widget
    (only mouse works so far)
  - fix pylints
- Pigweed features
  - DONE: hookup ingesting logs into self.logs
  - DONE: launch ipython rpc console correctly (not hardcoded)
  - DONE: make argparse options for above
  - log level filter
  - hdlc channel filter
  - auto discovery of setting based on .elf?
  - file browser to load elf / token database?

Change-Id: I1c49df7f2381023459b7166cb8a803b4b71b9182
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/35020
Reviewed-by: Joe Ethier <jethier@google.com>
Commit-Queue: Anthony DiGirolamo <tonymd@google.com>