Log Message:
sysutils/xplr: update to 0.8.4

0.8.4
=====
-Fixed search.

0.8.3
=====
-Fixed renaming files breaking the UI.

0.8.2
=====
-Fix rename breaking UI.

0.8.1
=====
-Fix exploring and escaping paths

This PR targets 2 pain points.
1. The `Explore` message was async, which caused some unexpected
   behavior. This was fixed by splitting `Explore` into `ExplorePwd`,
   `ExplorePwdAsync` and `ExploreParentsAsync`. `ExploreParentsAsync`
   is similar to the former `Explore`, which is mainly used when loading
   `xplr` for the first time. However, what we'll be using frequently
   are `ExplorePwd` and `ExplorePwdAsync` messages.
2. Files with spaces caused some unexpected behavior. This was fixed by
   escaping the paths properly. This also fixed focusing of a file after
   creating or renaming it.

Anothor breaking change is that `XPLR_PIPE_FOCUS_OUT` has been removed.
`XPLR_FOCUS_PATH` is all we need. So, the rule of thumb is if a variable
contains one liner value, it can be used directly from the env vars.
Variables that can contain multi-line values, will be exposed via the
pipes.

Minor changes are
- Add `switch_mode` mode to the global key binding help menu.
- Moved some UI related code from config.rs to ui.rs.
- Fixed compilation issue on `rustc 1.50.0`.

0.8.0
=====
-Breaking: The Explore message has been renamed to ExploreParentsAsync. While,
more relevant messages has been introduced: ExplorePwd and ExplorePwdAsync and.
-Breaking: $XPLR_PIPE_FOCUS_OUT has been removed. Use $XPLR_FOCUS_PATH instead.
-Fixed files with spaces causing issues (e.g. while renaming, focusing etc.)
-Added switch_mode mode to the global key binding help menu
-Moved some UI related code from config.rs to ui.rs.
-Fixed compilation issue on rustc 1.50.0.

0.7.2
=====
-Fixed displaying global help menu.
-Bound search mode tab key to ToggleSelection instead of Select.
-Logs will be displayed in ${PAGER:-less}

0.7.1
=====
-Use tab while in search mode to select files without losing the search input.
Similar to fzf.
-No socket errors after quitting the app.

0.7.0
=====
-Made panel config values nullable.
-Added fields general.panel_ui to define the common panel UI properties.

0.6.0
=====
-Now it's possible to define layouts and layout constraints based on screen
size and relative panel size.
-Now it's possible to define borders, panels and panel style.
-Now it's possible to define panel title and title style.
-Added messages SwitchLayout, SwitchLayoutBuiltin and SwitchLayoutCustom to
dynamically change the UI layout.
-Fixed overwriting margin in the config.
-add_modifier and sub_modifier has been renames to add_modifiers and
sub_modifiers and supports human values (e.g. Bold, Italic etc.) instead
of bits.
-From this commit, the output pipes will only refresh before executing an
external command.