git: Add fetchall alias

Added `git fetchall` (or `gfa`) alias which allows fetching the current
branch from all connected remotes simultaneously. May have some
unintended side effects when branches diverge, this is untested.

git/.config/git/config

@@ -9,6 +9,7 @@
   pushmerge     = "push -o merge_request.merge_when_pipeline_succeeds" # see https://docs.gitlab.com/ce/user/project/push_options.html # merge-when-pipeline-succeeds-alias
   last          = "diff HEAD~ HEAD"
   pushall       = "!git remote | xargs -I R git push R"            # push to all connected remotes
+  fetchall       = "!git remote | xargs -I R git fetch R"            # fetch from all connected remotes
 
 [commit]
   gpgsign       = true                                                 # sign commits as me

git/.config/sh/alias.d/git.sh

@@ -47,6 +47,7 @@ alias glog='git log --stat'
 alias gloog='git log --stat -p'
 
 alias gf='git fetch'
+alias gfa='git fetchall'
 alias gl='git pull'
 
 alias gpn='git push --dry-run'