Feature: Add weight to extensions in the gallery

[microbit-mark]

When an accessory maker has a lot of extensions that can be found by searching for the organisation eg 'Kitronik', it might be useful if they had a way of weighting the ones they think will be most popular or adding new products to the top of the search results.

If there isn't a way to do this already, maybe pxt.json could contain a value for weight that surfaces the extension in the top of the search.

A more granular search would being up specific extensions, but in the case of Kitronik, printed resources ask the use to search for 'Kitronik'.

[abchatra]

We should define an order in how extensions are displayed.

[riknoll]

i guess we can add an "organizationWeight" which weights within an organization on github. i hesitate to add a weight for all extensions, since i think that would lead to an arms race of people putting in the highest possible numbers to get to be at the top

[abchatra]

@riknoll can we show in the order they show up targetconfig? Like approved extensions in the targetconfig come first, among them first one listed in the targetconfig comes first?

[riknoll]

@abchatra do we want this to be a feature that people have to make a pr to change?

[abchatra]

@riknoll good point. Let me move this out of release. We can plan in the next releas.