[git] Add git pull autostash alias

Adds the gfma and gfra aliases with the `--autostash` flag.

modules/git/alias.zsh

@@ -97,7 +97,9 @@ if ! zstyle -t ':prezto:module:git:alias' skip 'yes'; then
   alias gfc='git clone'
   alias gfcr='git clone --recurse-submodules'
   alias gfm='git pull'
+  alias gfma='git pull --autostash'
   alias gfr='git pull --rebase'
+  alias gfra='git pull --rebase --autostash'
 
   # Flow (F)
   alias gFi='git flow init'