Cross platform support

[unsecretised]

This is regarding the windows-support branch and Linux support issue: #59

These are the things that whoever chooses to work on will have to be careful off:
For both OSes:

• Applications are stored in a different place in Linux, and hence you will need to figure out where and how the applications, and their icons should be loaded
• App opening logic + URL opening logic. For the google search feature, there needs to be a way to open the URLs
• Keeping the app the top most even when say a youtube video is fullscreened

For linux (wayland):

• Global hotkey doesn't work on wayland, and hence u will have to put the code for macos and windows behind a #![cfg()] gate, and vice versa for the wayland version
• Arboard (used for managing clipboard for rustcast) also has a few things that you will have to work out for Wayland and x11

For Windows:

• Config file will be stored somewhere else. Based on the work done on the windows-support branch right now by @Nazeofel , the config file will be stored at: LOCALAPPDATA\rustcast\config.toml

there may have been things i missed, so just add them here

[unsecretised]

Windows support is underway, and almost complete thanks to @Nazeofel and mnem42 (can't ping them cos they didn't take part in this)