Fixed border in file action menu

All IE versions are not able to properly upscale SVG icons unless the
said SVG files contain a "viewBox" attribute, which is not always the
case. Also we cannot guarantee that all third party apps will have this
attribute in their icons.

So for now, app icons will not be displayed in IE instead of broken
ones.

- calculate multiselect header width to exclude scrollbar
- call FileList._onResize() when sidebar is toggled ("appresized"), this
  also updates the breadcrumb width
- moved global getScrollBarWidth() to OC.Util namespace

* fixes #18627

Added hack that uses a "filter" CSS with explicit URL to fix the "New"
menu by scaling down icons and also fix the folder/filetype icon in the sidebar
by scaling it up.

If a response to a $.ajax() request returns a content type of "application/javascript"
JQuery would previously execute the response body. This is a pretty unexpected
behaviour and can result in a bypass of our Content-Security-Policy as well as
multiple unexpected XSS vectors.

Controls bar calculation needs to take the sidebar visibility into
account.

Recalculation is now triggered when sidebar is toggled, using a new
app-content event "appresized".

FileActionsMenu is now a backbone view.
The trigger and highlight handling is now done in the
FileActions.showMenu() method using events.

File actions now have two types "inline" and "dropdown". The default is
"dropdown".
The file actions will now be shown in a dropdown menu.

Tipsy also supported the `fallback` element which will now not work anymore. To enhance compatibility we shall also implement it in the shim.

Fixes https://github.com/owncloud/core/issues/17870

These should be used in the future instead of location.*.
It will make it possible to stub these methods for writing unit tests
and simulating different URL schemes.

When empty arguments are given, the leading or trailing slash was not
detected properly.

* fixes #12326 - the settings menu is closed now, because the event is executed