Add XDG support

Recommendations came from this blog post:
    https://blog.gitbutler.com/how-git-core-devs-configure-git/

Let's see how this works out lol

Test

apply-dotfiles

@@ -17,6 +17,9 @@ apply_dotfile sh
 apply_dotfile readline
 apply_dotfile screen
 
+apply_dotfile git
+apply_dotfile xdg
+
 apply_dotfile vim
 
 apply_dotfile ruby

bash/.bashrc

@@ -109,6 +109,9 @@ if [ -r "$HOME/.env" ]; then
   . "$HOME/.env"
 fi
 
+if [ -r "$HOME/.config/xdg/env" ]; then
+  . "$HOME/.config/xdg/env"
+fi
 
 # Source aliases, if they exist
 if [ -f "$HOME/.aliases" ] && [ -r "$HOME/.aliases" ]; then

git/.config/git/config

@@ -0,0 +1,25 @@
+[branch]
+	sort = -committerdate
+[column]
+	ui = auto
+[tag]
+	sort = version:refname
+[init]
+	defaultBranch = main
+[diff]
+	algorithm = histogram
+	colorMoved = plain
+	mnemonicPrefix = true
+	renames = true
+[push]
+	default = simple
+	autoSetupRemote = true
+	followTags = true
+[fetch]
+	prune = true
+	pruneTags = true
+	all = true
+[commit]
+	verbose = true
+[core]
+	excludefiles = ~/.config/git/ignore

installers/install-nix.sh

@@ -40,6 +40,7 @@ NIX_CONF_FILE=${NIX_CONF_DIR}/nix.conf
 mkdir -p ${NIX_CONF_DIR}
 cat <<EOF > ${NIX_CONF_FILE}
 experimental-features = flakes nix-command
+use-xdg-base-directories = true
 EOF
 # Conditionally add a link to system certificates for nix
 if [ -f /etc/ssl/certs/ca-certificates.crt ]; then

xdg/.config/xdg/env

@@ -0,0 +1,11 @@
+export XDG_DATA_HOME="${HOME}/.local/share"
+export XDG_CONFIG_HOME="${HOME}/.config"
+export XDG_STATE_HOME="${HOME}/.local/state"
+export XDG_CACHE_HOME="${HOME}/.cache"
+
+# Set environment variables to force programs to respect XDG that do not by default
+export SCREENRC="${XDG_CONFIG_HOME}/screen/screenrc"
+export GNUPGHOME="$XDG_DATA_HOME"/gnupg
+export MYSQL_HISTFILE="$XDG_DATA_HOME"/mysql_history
+export INPUTRC="$XDG_CONFIG_HOME"/readline/inputrc
+export IRBRC="$XDG_CONFIG_HOME/irb/irbrc"