API: Load casks/formula from JSON with missing keys

[apainintheneck]

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Related to the discussion in #16410 and the first bullet point in #16410 (comment).

We'd like to reduce the size of the API JSON and to do that we are going to remove unused and/or blank elements from the cask/formula definition. This will reduce the amount of data that has to go over the wire and make it easier to load this data into memory.

Beyond the code I've changed here, there are a few other spots that I've decided not to update to handle null values because they should always be present anyway and if they're missing, we'll have bigger problems to deal with.

brew/Library/Homebrew/formulary.rb

Line 288 in 080e61f

bottles_stable["files"].each do |tag, bottle_spec|

brew/Library/Homebrew/cask/cask_loader.rb

Line 338 in 080e61f

json_cask[:artifacts].each do |artifact|

[MikeMcQuaid]

Makes sense, great work as usual @apainintheneck!