Remove uncurried chapter and update existing docs to uncurried

[fhammerschmidt]

Also removed a lot of final units in example code.

[ryyppy]

A few comments / nitpicks. But generally, looking great!

[ryyppy]

I don't like this... is this somewhat possible to fix? @cknitt @cristianoc

[ryyppy]

I think the main concern was mostly about genType relying on bs.js when I am not mistaken? Nowadays genType reads the rescript.json anyways, so I assume some constraints regarding configuring the .js extension should be lifted?

[ryyppy]

Looks good! Only question I have is how we treat the (.) => {} syntax in the docs.

As I understand, everything is now an uncurried function. But at some point ppl will see the syntax and wonder what it is.

[fhammerschmidt]

Suggestion:

• Remove all occurences where (.) it is used (e.g. this-based callbacks)
• Mention in https://rescript-lang.org/syntax-lookup#uncurried-function that it is only relevant for <11 or if uncurried is deactivated explicitly and also mention to use the older docs if one prefers currying. Not ideal, but it should make it clear that uncurried is the default way in ReScript going forward.
• Also https://rescript-lang.org/syntax-lookup#uncurry-decorator is pretty much useless now, that chapter can also have such a warning