feat: Add ability to fetch custom IoC container

[alxwrd]

Hey! Happy hacktoberfest 🎃! This closes #779.

This adds a check to see if iocContainer is a function and if it is, calls it with the request to resolve the IoC container. This means that the iocContainer can be created/updated/fetched per request.

The reason I've added in the check to see if it's a function is to avoid being a breaking change.

I will need to raise a PR over at tsoa-community/docs to document this change.

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[WoH]

Alright, I think I'm fine with the changed API as a new way to create containers per request. A remaining DX issue is the typing thought. We should at least expose type information what the container can be (function request => Container or Container) and export an interface a developer can implement and be sure.

[alxwrd]

I can add the following for typing information.

export interface TsoaIocContainer { get<T>(controller: any): T;
export type TsoaIocContainerMethod = (request: any) => TsoaIocContainer

This would allow the users ioc module to type the method or container if they desired.

// src/ioc.ts
export const iocContainer: TsoaIocContainerMethod = (request: Express.Request): TsoaIocContainer => {
    return new Container();
};

Tsoa itself could then use these types in the routes file.

const container: TsoaIocContainer = typeof iocContainer === 'function' ?
    (iocContainer as TsoaIocContainerMethod)(request) : iocContainer;

const controller: any = container.get<{{../name}}>({{../name}});

[alxwrd]

@WoH My last 2 commits should address the typing issue.

I have a change ready to add the typings the new test included in this PR, but would like the typings applied to the other tests as well?

[WoH]

@WoH My last 2 commits should address the typing issue.

I have a change ready to add the typings the new test included in this PR, but would like the typings applied to the other tests as well?

My bad, didn't notice the last commits.

[WoH]

Alright, this looks pretty good now, only some nitpicking left. Great job!

[WoH]

LGTM

[alxwrd]

hey @WoH. Thanks for your review and your help ironing this out. Do you need anything else from me, or can this be merged?