Feature: Add custom command & label support (#945)

## What are the changes about?

Adds customizable commands and labels to ly.
Solves https://codeberg.org/fairyglade/ly/issues/905.

Since Ly doesn't use INI headers. I use them exclusively for declarations of custom commands and labels.

### Commands

Bind a keybind to a command, and add a hint to the HUD. Useful for use cases like display brightness, switching between GPUs, etc.

Supports localization in the `name` field only. ex: where `lang = es`: `$brightness_up` => `bajar brillo`

Declared in config.ini with the following:

```ini
[cmd:F8]
name = custom command 2
cmd = touch /tmp/ly.gaming
```

### Labels

Add a label to the HUD. As specified in #905.
The text of the label corresponds to the output of the command specified in `[lbl:NAME]`.
Only shows the first line of the output.

Declared in config.ini with the following:

```ini
[lbl:kernel]
cmd = uname -srn
refresh = 0
```

Example to add to the config.ini:
```ini
# Declare a command with the F8 binding.
[cmd:F8]
#The name of the command to show up in Ly.
name = custom command
cmd = touch /tmp/ly.gaming

# Declare a label with an ID. This ID should be unique across all labels.
[lbl:kernel]
cmd = uname -srn
# In frames, the time to re-run the command and update the label. If 0, only run once- do not refresh.
refresh = 0

# Once you're done setting up labels and commands, add an empty header
# below to continue configurating the rest of Ly.
# Put other settings not belonging to custom commands/labels below here.
[]

```

## Pre-requisites

- [x] I have tested & confirmed the changes work locally

![image](/attachments/f9373ac9-567e-4f47-987c-1df6f4ee0d84)

Reviewed-on: https://codeberg.org/fairyglade/ly/pulls/945
Reviewed-by: AnErrupTion <anerruption+codeberg@disroot.org>
Co-authored-by: RadsammyT <radsammyt@gmail.com>
Co-committed-by: RadsammyT <radsammyt@gmail.com>

res/lang/ar.ini

@@ -3,6 +3,9 @@ brightness_down = خفض السطوع
 brightness_up = رفع السطوع
 capslock = capslock
 
+
+
+
 err_alloc = فشل في تخصيص الذاكرة