GeezerVison

Fixes #1733

printUnaryExpression printed the operator and the operand next to each other, so a negation whose operand also starts with - came out as --, which Lua reads as the start of a comment:

let a = 5;
return -(-a);

local a = 5
return --a   -- returns nothing

The same thing happens with -(-5), -(-(-a)), and with a const enum member that has a negative value (const enum E { A = -1 }; -E.A printed --1, because the inlined value is a negative numeric literal).

The printer now adds a space when the operator is - and the printed operand starts with -, so these print as - -a, - - -a, - -1. Other unary operators and operands are printed as before, so no snapshots change.

Tests: added functional tests in test/unit/expressions.spec.ts for -(-a), - -a, -(-(-a)), -(-a) * 2, -(-5), and the const enum case. All 6 fail before the change and pass after. npm test (lint + full jest run) passes.