Add File.executable? for Windows

[nof1000]

No description provided.

[hugopl]

See spec/std/file_spec.cr:135, there are some tests tagged as pending there for this that should be unskipped.

[straight-shoota]

@nof1000 Looks good 👍 Would you care enabling the mentioned specs for this?

[straight-shoota]

@nof1000 Are you still up to continue with this?

[HertzDevil]

This part can probably be enabled for Windows:

crystal/src/process/executable_path.cr

Lines 40 to 51 in b10165e

	private def self.is_executable_file?(path)
	unless File.info?(path, follow_symlinks: true).try &.file?
	return false
	end
	{% if flag?(:win32) %}
	# This is *not* a temporary stub.
	# Windows doesn't have "executable" metadata for files, so it also doesn't have files that are "not executable".
	true
	{% else %}
	File.executable?(path)
	{% end %}
	end

[oprypin]

@HertzDevil Enabled in what sense?
Are you referring to the part that says it's *not* a temporary stub?
Well, I'm saying again, that implementation is complete and passes https://github.com/crystal-lang/crystal/blob/master/spec/manual/find_executable_spec.cr

[sdogruyol]

Thank you @nof1000 🙏