Default `--watcher` by "config ron" file

**Is your feature request related to a problem? Please describe.**
Starting `--watcher` mode depends on manual input or shell aliasing on the system.

**Describe the solution you'd like**
Configure default `--watcher` mode via 'ron' configuration file.

**Describe alternatives you've considered**
Create an alias in the system shell configuration for `gitui --watcher`

**Additional context**
#### Software version

gitui 0.26.3 (95e1d4d)

#### Operating system

Linux 6.8.0-39-generic

#### Compile time information

- Profile: release
- Target triple: x86_64-unknown-linux-musl
- Family: unix
- OS: linux
- Architecture: x86_64
- Pointer width: 64
- Endian: little
- CPU features: fxsr,sse,sse2
- Host: x86_64-unknown-linux-gnu

#### Environment variables

```bash
SHELL=/bin/bash
EDITOR=
GIT_EDITOR=
VISUAL=
```

#### Command-line

```bash
gitui --bugreport
```