Formatter should normalize symbol literals and similar fragments

[HertzDevil]

Currently, the formatter always leaves SymbolLiterals in the source code unchanged:

crystal/src/compiler/crystal/tools/formatter.cr

Lines 444 to 450 in 752c57b

	def visit(node : SymbolLiteral)
	check :SYMBOL
	write @token.raw
	next_token
	false
	end

This means all of the following symbols remain after formatting, even though they are equal to each other:

:foo
:"foo"
:"fo\o" # invalid escape

Other similar fragments with redundant quotation marks that the formatter doesn't remove are:

def foo("x" y)
end

foo("x": 1)

NamedTuple("x": Int32)

{"x": 1}

Unifying these forms to the quoteless variant is desirable as it simplifies source code searching. This means:

• Unnecessary quotation marks should be removed;
• Invalid escape sequences should be removed; (only symbol literals are suspectible to this)
• The formatter should apply the fix in Parser vulnerable to Trojan Source attack #11392 here too.

Note that macro interpolation already applies the first two normalizations to all those fragments already.

[meatball133]

I want to give this a shot.