This commit fixes a bug introduced with https://github.com/odoo/odoo/pull/28251:
When opening the ace editor on page load thanks to the #ace-view-editor
URL hash, a JS error occurred preventing the editor to open.
This was due to the way actions were executed on page loading:
- Menu elements are initialized and can handle actions
- On initialization, the ace menu tried to launch the editor
- First, it asked that all widgets are closed (see mentioned PR)
- The website handled that action demand by asking everyone to close
their widget
- The 'new content' menu tried... and failed as referenced a variable
which would only have been created in the start method.
Conclusion: before handling actions, all action-capable widgets should
be started. This is what this commit does: when receiving an action
demand, we first wait for the action handler to be fully started. This
implied another change: before, many menus were waiting for the result
of an action to notify that their start method is finished... this
would cause a deadlock in the new system so those were removed, this did
not make much sense anyway (if the result of that starting action has to
be known, a dedicated event/method should handle that).
closesodoo/odoo#28364