Show [[count]] var for arrays

[TwitchBronBron]

In the debug protocol, we know the length of the array ahead of time, so we should show the [[count]] variable. Code like this would work:

v.namedVariables = 1;

//add a virtual [[count]] prop if the array children are present
if (result.children && result.children?.length === result?.elementCount && result?.elementCount === 3) {
    v.childVariables.push(
        this.getVariableFromResult({
            name: '[[count]]',
            value: result?.elementCount.toString(),
            type: 'integer',
            highLevelType: HighLevelType.primative,
            evaluateName: `${result.evaluateName}.count()`,
            presentationHint: 'virtual',
            keyType: undefined,
            children: undefined,
            elementCount: 0
        }, frameId)
    );
}

The issue right now, is for arrays, we end up with both indexed and named variables, so our variable lookup pipelines don't currently support splitting them out between the two. So that'll need done too.