Remove symbol overloads of Colorize color methods for symbol auto-casting

[straight-shoota]

Colorize methods receiving a color (#fore and #back) have overloads receiving a Symbol parameter which is manually mapped to values of ColorANSI. This implementation predates the symbol auto-casting of enum values.

This patch removes the overloads with Symbol typed parameters which leaves the overloads receiving a Color parameter. This type is a union including the enum ColorANSI which enables symbol auto-casting for color values.

The problem is: it's a breaking change. If the API is used with symbols that are not directly created from literals, there will be a compile time error. This is good and intended because it adds type safety (you can know at compile time whether a value is valid). But it's still a breaking change that destroys valid use cases which would require changes to user code (as demonstrated by the changes in samples/2048.cr and src/spec/dsl.cr for example). So I believe we can't merge it just like that.
The only option is to leave the removed overloads in with a deprecation notice. That's not ideal though because the deprecation warning even triggers for usages that are compatible with the auto-casting method. But the symbol overload takes precedence over auto-casting. The only way to deactivate deprecation warnings is using a named argument: fore(fore: :green).

Are there any other ideas? We could use a feature flag but I think would be silly for such a minor thing.

This patch has been extracted from #7690.

[HertzDevil]

This is observed in #11020 and also in:

crystal/src/time/location.cr

Lines 147 to 156 in 9e52dd6

	# Returns the `#offset` formatted as `+HH:mm:ss`.
	# When *with_colon* is `false`, the format is `+HHmmss`.
	#
	# When *with_seconds* is `false`, seconds are omitted; when `:auto`, seconds
	# are omitted if `0`.
	def format(with_colon = true, with_seconds = :auto)
	String.build do |io|
	format(io, with_colon: with_colon, with_seconds: with_seconds)
	end
	end

I don't know any way other than as part of some other flag disallowing Symbol-typed variables altogether.

[jkthorne]

should there be a deprecation warning for this?

[HertzDevil]

As mentioned in the OP, the mere existence of a Symbol-accepting overload will trigger deprecations even for arguments that autocast to Color due to overload ordering.