Use qualified method name for calls to Kernel#load

[pyrmont]

Rouge loads various components of the library using Kernel#load. In certain situations, this can cause issues where load is redefined at the global level. To ensure maximum compatibility with other libraries, this PR replaces all calls of load with qualified calls to Kernel::load.

[pyrmont]

This is primarily intended to fix the issue identified in asciidoctor/asciidoctor#3623.

[mojavelinux]

To be consistent with calls elsewhere in the library, I think the dot-notation syntax for a static method should be used instead: Kernel.load.

[jneen]

I think it's fine as it is.

[jneen]

LGTM, @pyrmont, merge as you like :]

[pyrmont]

I can't really see a material difference but it does seem more semantically correct to call Object::send rather than Object.send so I cleaned that up. Also took the opportunity to remove redundant logic in the visual sample app.

[ashmaroli]

Of course you know about the following better than I do, but leaving a comment just in case you overlook them..
Rouge also calls load within various lexers. For example:

rouge/lib/rouge/lexers/gherkin.rb

Lines 20 to 24 in 2b704db

	# self-modifying method that loads the keywords file
	def self.keywords
	load File.join(Lexers::BASE_DIR, 'gherkin/keywords.rb')
	keywords
	end

[pyrmont]

Thanks Ash! Will make sure to include those as well :)

[mojavelinux]

One thing we've learned from the incident that led to this request is that the top-level load method can be replaced without any warning, even when Ruby warnings are enabled. I think that provides some additional justification for why using Kernel.load is more robust.

[pyrmont]

Thanks everyone. Got this merged in.

In terms of pushing it out in a gem, my plan is to release this as part of the other updates coming in v3.19.0. On our monthly cadence, that's scheduled for release on Tuesday 12 May.