Asynchronous component initializers about tsdi HOT 4 CLOSED

@Prior99 Thanks for reporting. I'll have to think about it.
Its a good use case which will require a bit more API I think.

Could be a problem in tsdi object graph creation.

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My idea to solve this is to wait for all injects to be created and have their initializer executed. Initializers which return a promise should be awaited in this case.

The biggest problem right now is the default lazy injection. The db above need to be eager injected instead of lazy, so the component is created before first access and could be awaited.

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@Prior99 As of #209 this issue is partially solved. The part missing are the factories. By the synchronous nature of the new keyword in javascript and therefore the synchronous nature of dependency injection it is not possible to implement asynchronous factories.

You may work around this with this pattern:

@component
class Database {
    private databaseConnection: DatabaseConnection;

    @initialize
    async connect() {
        this.databaseConnection = await connectToDatabase();
    }

    get connection(): DatabaseConnection {
        return this.databaseConnection;
    }
}

@component({ eager: true })
class Api {
    @inject private db: Database;

    @initialize
    public initialize() {
        this.db.connection.query(...); // `db` is now `undefined`.
    }
}

Since Api.initialize() is only called if all injected dependencies are itself done you can be sure that this.db.connection is ready in your example.
Hope that help a bit.

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Released in v1.0.0-alpha.0
This is alpha, because of the breaking change and I like to take the chance and rewrite bigger parts.

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