Make input$, disabled$ and output$ optional (feat-rewrite v6.0.0)

[temka1234]

In rewrite version make fields input$, disabled$ and output$ as optional.
Sometimes i don't need input$ or disabled$ for root forms.

[maxime1992]

Hi @temka1234 👋

not sure how I feel about this. I believe in most cases we would want this and having some type safety forcing us implementing it is IMO the right way to go.

If you don't need them, it's super simple to just pass

• of(null) for input$
• of(false) for disabled$

Does that seem reasonable for you?

[zakhenry]

I think I'm with @temka1234 here to be honest - I had quite a few cases recently where I found it annoying that I had to declare a no-op observable for something that didn't make sense in the context of the component I was developing

[maxime1992]

There's also something that is worrying me, but I got lazy and didn't want to search for it as I couldn't remember where I came across that 😅. So thanks for challenging this @zakhenry because I believe the real root cause of me not wanting this is a bigger concern than this issue.

I've raised a dedicated issue for what I'm about to talk about because I do not want it to be lost in this thread, please give a read to #200.

I'm afraid that (at least for now), making the input optional would be source of issues.

Once 200 is solved let's make them optional 👍.