Add ability to run function after save

This adds the ability to run a function after a capture. This is
configured with the `after_save` key. The function takes in the buffer
number for the capture buffer (not the target file/buffer) and the data
that is passed into the autosave command for the capture.

Author: pritchett

lua/neorg/modules/external/capture/module.lua

@@ -86,14 +86,15 @@ module.private = {
                 path = item.path,
                 query = item.query,
                 datetree = item.datetree,
+                after_save = item.after_save,
             }
         end
 
         local item_is_enabled = function(item)
             return item.enabled == nil or type(item.enabled) == "function" and item.enabled(bufnr) or item.enabled
         end
 
-        for _, item in ipairs(conf.templates) do
+        for _, item in ipairs(conf.templates or {}) do
             if item_is_enabled(item) then
                 if item.name and item.name ~= "" then
                     table.insert(items, item.description)
@@ -317,6 +318,9 @@ module.on_event = function(event)
                     calling_bufnr = calling_bufnr,
                     on_save = function(bufnr, passed_data)
                         module.private.on_save(bufnr, passed_data)
+                        if type(data[idx].after_save) == "function" then
+                            data[idx].after_save(bufnr, passed_data)
+                        end
                     end,
                 },
             })