manage keyboard shortcuts across apps, avoiding browser defaults

Summary: Manage keyboard shortcuts with attention to the following:

1. Shortcuts must be consistent across applications, e.g. the "expand all accordions" shortcut must be the same in every app. Ideally, this can be implemented in one place and leveraged everywhere, rather than (re)-implemented in every app.

2. FOLIO shortcuts (probably) should not override a browser's built-in shortcuts. This may be hard/impossible/frustrating as browsers update and add new shortcuts for obscure functions, and as shortcuts vary across different locales and operating systems. Nonetheless, we need to be aware of this, so that we can make decisions to override built-ins deliberately rather than accidentally.