study & choose best approach for handling ng observables

[nongrata081]

• [ ] add observables directive for handling multiple observables in a neat way (in order to prevent multiple subscription to a single observable in angular template) from Having fun with Structural Directives in Angular @ 2. The Observables Directive

related no templateRef issue

for template-side handling of observables consider:

https://netbasal.com/diy-subscription-handling-directive-in-angular-c8f6e762697f

https://github.com/angular/angular/issues/15020

https://github.com/angular/angular/issues/12237

https://github.com/angular/angular/issues/13061

https://stackoverflow.com/questions/38582293/how-to-declare-a-variable-in-a-template-in-angular

https://blog.angularindepth.com/having-fun-with-structural-directives-in-angular-69b4d229ad93

study if this is applicable https://github.com/nongrata081/devkit/issues/76