feat: pass field to FormlyFieldConfigPresetProvider.getConfiguration

[MaxKless]

refer to #3456 for details

@aitboudad the problem is that reverseDeepMerge completely ignores arrays, which sucks for the fieldGroup merging use case. So I copied and modified it to also handle arrays.

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[aitboudad]

I think its better to keep the reverseDeepMerge, for two main reasons:

1. It may introduce a breaking change
2. The order of merging an array is relevant for some use-case and that's why I do prefer to let user decide how to merge their data.

[MaxKless]

If I keep reverseDeepMerge as it is, this example you provided won't work anymore:

export class AdressPresetProvider {
    constructor(@Inject(ADDRESS_OPTIONS) private adressOptions: string[]) {}
    getConfiguration(f: FormlyFieldConfig): FormlyFieldConfig {
        return {
          fieldGroup: [ 
            { key: 'province', ... },
            { key: 'city', ... },
            ...f.fieldGroup,
          ]
        }
    }
}

I put some logs into preset-subsitution.extension.ts to show what's happening:

you can see that the preset merges the fieldGroup correctly but it's ignored by reverseDeepMerge.

Do you have a proposal for how to solve this?

[aitboudad]

I see, so it seems a blocking part for now anyway I'll try to further check later and let you know if I find something!