Allow `~` expansion for config files and folders

[nachtjasmin]

(Almost the same as #344, just for a different setting.)

Hi, I want to share my Pacman config across my systems to have the same local repository and settings everywhere. Therefore I've put the custom pacman.conf along with the paru configuration into my dotfiles and referenced the pacman config like this:

PacmanConf = "~/.config/pacman/custom.conf"

Unfortunately, this doesn't work. Replacing the tilde with $HOME doesn't work either. I want to keep it portable without cluttering the /var/ or /opt folders. Therefore an expansion of ~ or $HOME to the current home directory would be a nice addition.

[jdujava]

This would also be useful for specifying local PKGBUILD repositories via

Path = ~/path/to/directory

[Morganamilo]

I'm for this, just once I think up a clean way to implement it.