In prep for future PHP changes as per RFC
https://wiki.php.net/rfc/deprecate_dollar_brace_string_interpolation

…development

- Occurred on system request path usage (Primarily on guest login
  redirection) when a custom path was not in use.
- Added test to cover.

For #3404

Not yet an actual added language yet due to low translation rate.

Tiny header

- Means we can use these simpler types in API response, As desired in #3377.

Closes #3395

Made the following changes, many of these are just to align with
existing conventions.

- Updated urls to be hypenated, instead of underscored, to match other system endpoints.
- Updated URL parameter to be `deletionId` instead of `id`, and removed the ID-based comment on controller methods, so the required ID model is clear from the URL alone, since its not clear from the URL endpoint alone like existing endpoints. This follows the pattern used in the "web" routes.
- Added extra detail on some controller method comments, and copied permission comment to each method.
- Removed existing field visibility mechanisms to use simpler model-based visibility since we didn't need anything too special here (After some of my other changes).
- Allowed the "deletable" model to be shown in response to provide a little more detail on the main deleted item.
- Updated parent/child-count loading to be on the "deletable" model instead of additional properties which results in simpler controller logic and enforces the idea these are relations on the deletable, not the deletion itself. It also removes additional exposure of model namespacing.
- Updated (int) casts to intval, just since that's our most common conversion method in the codebase.
- Testing: Removed `actingAsAuthorizedUser` and used the admin user instead to prevent extra auth steps on each test.
- Testing: Cut logic/data-checks from tests if already covered by other tests.
- Testing: Added simple assertions for delete/restore response data.
- Examples: Updated list example to reflect changes.

Review of PR #3377
To be followed up with changes to polymorphic relations to hide
namespacing.

Updated custom request overrides to better match original intent

Page editor switching

Add data streaming where beneficial to reduce memory usage

Made it possible to configure draw.io/diagrams.net integration

- Works better to avoid bad assumptions when showing the editor based
  upon content type.
- Also updated some previous tests to cleaner format.

- Also tweaked some editor revision table styles and merged some
  sections to reduce space usage.

Added new editor public event to hook into draw.io configuration step.
Required change of embed url to trigger the configure step.