Feature request: share and shareReplay

#### Feature request

> Please describe the feature.

rxjs is evolving and I suggest keeping up with it.
In particular I suggest to implement new [share](https://rxjs.dev/api/index/function/share) and [shareReplay](https://rxjs.dev/api/index/function/shareReplay) methods.

This feature also can fix #1218.

> Which next library version (i.e., patch, minor or major)?

Any.

> What are the platform(s), environment(s) and related component version(s)?

All.

> How commonly is this feature needed (one project, several projects, company-wide, global)?

global