feat(gitignore): add caching to gi completion

Adds a cache policy for the `gi` command completion function, i.e.
`_gitignoreio`. Previously, every completion call would request the list
endpoint of gitignore.io over the network, resulting in a delay between
pressing <Tab> and the autocomplete options showing up.

Since we don't expect the gitignore.io templates to change that
frequently, configured the cache policy to expire after 7 days.

Fixes #13736

Signed-off-by: Rishvic Pushpakaran <rishvic@gmail.com>

plugins/gitignore/gitignore.plugin.zsh

@@ -13,9 +13,28 @@ _gitignoreio_get_command_list() {
   _gi_curl "list" | tr "," "\n"
 }
 
-_gitignoreio () {
-  compset -P '*,'
-  compadd -S '' $(_gitignoreio_get_command_list)
+__gitignoreio_caching_policy() {
+  local -a oldp
+  oldp=("$1"(Nm+7))
+  (($#oldp))
 }
 
-compdef _gitignoreio gi
+_gitignoreio() {
+  compset -P '*,'
+
+  local cache_policy
+  zstyle -s ":completion:${curcontext}:" cache-policy cache_policy
+  if [[ -z "$cache_policy" ]]; then
+    zstyle ":completion:${curcontext}:" cache-policy __gitignoreio_caching_policy
+  fi
+
+  local -a _gi_list
+  if _cache_invalid gi-list || ! _retrieve_cache gi-list; then
+    _gi_list=(${(f)"$(_gitignoreio_get_command_list)"})
+    _store_cache gi-list _gi_list
+  fi
+
+  compadd -S '' -a _gi_list
+}
+
+compdef _gitignoreio gi