reportAllStartupErrors

Has decorators keep the startup errors they find, as a bot built with startupErrors: 'all' does, so a testing module reports every one at once.

Call it once in the test runner's setup file, before any test imports a controller: a decorator runs when its class is defined, as its file is imported. A decorator given what it cannot use then throws nothing as the file loads, and MeoCordTestingModule.create(...).compile() logs every startup error of the classes it runs, each with its handler and file, then throws the first. Without it, a decorator throws its error as its class is defined.