feat(config): fish configs

config/fish/functions/has_keg.fish

@@ -0,0 +1,23 @@
+# @halostatue/fish-brew/functions/has_keg.fish:v3.2.1
+
+function has_keg --description 'Test if the named keg or kegs are installed'
+    command --query brew
+    or return 1
+
+    argparse --min-args 1 A/all -- $argv
+    or return 1
+
+    set --function found 0
+
+    for keg in $argv
+        if test -d (brew --prefix)/Cellar/$keg
+            set found (math $found + 1)
+        end
+    end
+
+    if set --query _flag_all
+        test $found -eq (count $argv)
+    else
+        test $found -ne 0
+    end
+end