Reason: [Syntax] Semicolon rules confusing

[chenglou]

This could go on and on so I'll only file one issue for it. I'll collect all the confusing parts of semicolon here.

• In a switch/catch block there shouldn't be a semicolon like this:

switch x {
| a => 5;
}

• In a local open, there shouldn't be one:

MyModule.(bla;)

• Braces not followed by semi:

let f => blablabla
let a = 5;

if (true) {
  ...
}
let a = 5;

And this is a bit nuanced, formatting this will succeed by with the wrong result (f slurped inside else block):

if (true) {a} else {b}
f ();

[mrkaspa]

It will be good to have ASI or remove the semicolons from the language and have the return keyword may be