Bug fixes

Changes since 8.x-2.3:

• Issue #3059081 by Boobaa: Add Composer instructions
• Issue #3061420 by mxr576: Report missing Swagger UI library in a better way, plus small refactoring
• Issue #3063895 by yce, balazswmann: Set oauth2RedirectUrl option

PETs are not translatable.
Fixed token parsing error with the latest core.

Issue #3012663 by alonaoneill: Capitalize the name of the module in .info.yml file.

Issue #3061990 by tamarpe: Enable support for the new embed code of issuu viewer.

• #3061368: Proxy support: Add support for Drupal proxy settings
• Upgrade @sentry/browser to version 5.4.3