InjectionToken<...> for public providers in piral-ng

[hwanders]

New Feature Proposal

Add typed InjectionToken<...> constants to piral-ng and use them when providing piral, Props and Context using those tokens in the dependency injection container.

Description

For downward-compatibility the string-based providers should probably be kept. The relevant source code parts are:

• module.ts: https://github.com/smapiot/piral/blob/1c113ff5fb1b3c9faae24dbba09c750c5e75cbc2/src/converters/piral-ng/src/module.ts#L40
• standalone.ts: https://github.com/smapiot/piral/blob/1c113ff5fb1b3c9faae24dbba09c750c5e75cbc2/src/converters/piral-ng/src/standalone.ts#L49

Background

Some application developers prefer the new inject(...) funtion over the classic @Inject(...) annotation. inject is typed more strictly, it does not allow a simple string parameter anymore, like @Inject. So writing inject('piral') will fail in a type checking error.

Since the token passed to inject must exactly match the one used as provide key, developers currently can not use the the inject function without using type-avoiding hacks (like inject('piral' as any)).

Example

The following is an ad-hoc change, without even compiling/building Piral. https://github.com/hwanders/piral/commit/84347a912fda06914a6d4048d018f567b281086b

[FlorianRappl]

Sounds great - want to make a PR?