Improve luau.set rendering for string members (keys) which are valid identifiers

[osyrisrblx]

Input

const set = new Set(["a", "b", "c", "this has spaces", "1234"]);

Before

local set = {
	["a"] = true,
	["b"] = true,
	["c"] = true,
	["this has spaces"] = true,
	["1234"] = true,
}

After

local set = {
	a = true,
	b = true,
	c = true,
	["this has spaces"] = true,
	["1234"] = true,
}