Bring context to standard components

[Diggsey]

Description

• Moves ContextProvider to yew crate.
• Adds context() method to ComponentLink/Scope/AnyScope
• Switches ComponentProvider to use explicit unsubscription via a guard.
• Re-implements use_context via scope.context()
• Removes Rc<_> wrapper from context values, with the rationale that if the user wants that, they can add it themselves.

Fixes #1647

Checklist

• I have run cargo make pr-flow
• I have reviewed my own code
• I have added tests

[Diggsey]

This approach is more powerful than using a ContextConsumer component, and allows you to update component state in response to context.

If desired, a ContextConsumer component could trivially be implemented on top of this though.

[siku2]

What do you think, @hamza1311?
Especially with regards to #1841.

[ranile]

What do you think, @hamza1311?
Especially with regards to #1841.

@siku2, This builds upon code that has already been re-worked in #1780. I think that PR should be merged, yew-functional should be merged into yew and then PR should be merged.

I haven't looked too closely at the implementation yet but from what I can tell, it looks good but I don't believe it should be merged just yet.

[siku2]

Now that that's done, would you mind updating this PR, @Diggsey?

[Diggsey]

Done 👍