Additional Extension Provider

[elbakerino]

A default available extension provider would be great to enable e.g. custom component rendering where all supporting components can be enhanced with full components.

Use cases which could benefit from it:

info usecase: an available placeholder in textfield, list, options, selects etc., which would consist of an info component, which may either render a button that opens an dialog or as inline description or (any) other way. This way some apps could also add markdown support with a free chose of the markdown renderer, others may use mustache etc. But the textfield etc. does not contain any logic for the placeholder, only "if placeholder exists, render it and pass down schema"

onKeyPress / onBeforeChange / onClickLabel / onClickInput handlers which are applied to all widgets, passed down once, could enable features like warn in demo mode / opening for readable-writable (#78) / global read-only mode / undo-redo store changes with CTRL+Z

[elbakerino]

Added extra extension provider & context, custom by default. is hard wired / included in UIStoreProvider.

export interface FormConfig {
    something: string
}

const Comp1 = () => {
    return <UIStoreProvider<FormConfig>
        // all default props + FormConfig
        something={'one-thing'}
    />
}

const Comp2 = () => {
    const {something}= useUIConfig<FormConfig>()

    return null
}

Useful for generator-wide, but not for-all-generators, usages.

Note: for most use cases the custom UIMetaProvider extension is more useful, like used in Read-or-Write