[meta] tune luacheck for norns

[pq]

currently luacheck is not tuned for norns and (some) "idiomatic" scripts are very linty.

the reported issues fall into a some rough categories.

1. legitimate
2. legitimate but fussy
3. bogus
4. bogus but potentially legitimate

legitimate issues (1) are good as is but fussy ones (2) should probably be hidden by default w/ an opt-in. entirely bogus issues (3) should just get filtered out whereas we should strive to make the ones that are potentially valuable (4) legitimate.

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follow-ups to address:

bogus lints

• recognize norns globals (recognize norns globals #2)

fussy lints

• consider a strict (opt-in) luacheck mode (consider a strict (opt-in) luacheck mode #3)