Pad: Move `padLoad` hook invocation to `PadManager.js`

This puts global state change logic with the rest of the global state
management logic. This also makes it possible to create temporary Pad
objects without triggering plugin actions.

doc/api/hooks_server-side.md

@@ -175,14 +175,15 @@ Things in context:
 
 This hook gets called when a new pad was created.
 
-## padLoad
-Called from: src/node/db/Pad.js
+## `padLoad`
 
-Things in context:
+Called from: `src/node/db/PadManager.js`
 
-1. pad - the pad instance
+Called when a pad is loaded, including after new pad creation.
 
-This hook gets called when a pad was loaded. If a new pad was created and loaded this event will be emitted too.
+Context properties:
+
+* `pad`: The Pad object.
 
 ## padUpdate
 Called from: src/node/db/Pad.js

src/node/db/Pad.js

@@ -366,8 +366,6 @@ Pad.prototype.init = async function (text) {
 
     await this.appendRevision(firstChangeset, '');
   }
-
-  hooks.callAll('padLoad', {pad: this});
 };
 
 Pad.prototype.copy = async function (destinationID, force) {

src/node/db/PadManager.js

@@ -22,6 +22,7 @@
 const CustomError = require('../utils/customError');
 const Pad = require('../db/Pad').Pad;
 const db = require('./DB');
+const hooks = require('../../static/js/pluginfw/hooks');
 
 /**
  * A cache of all loaded Pads.
@@ -141,6 +142,7 @@ exports.getPad = async (id, text) => {
 
   // initialize the pad
   await pad.init(text);
+  hooks.callAll('padLoad', {pad});
   globalPads.set(id, pad);
   padList.addPad(id);