Fix corner cases of re-opening aliases

[vinistock]

When an alias is re-opened with the class or module keyword, we need to ensure that we're adequately following it, so that we re-open the target and not the alias itself.

For example:

class Foo; end

ALIAS = Foo

class ALIAS
  def bar; end
end

This creates Foo#bar() and not ALIAS#bar().

[vinistock]

• Include RBS paths when indexing workspace #609
• Add integrity check for owner relationships #592
• Avoid creating singleton classes for non-namespace targets #623
• Auto promote when creating constants inside namespace #622
• Fix corner cases of re-opening aliases #621 👈 (View in Graphite)
• Follow aliases when they are used in mixins or parent classes #620
• main

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[vinistock]

Merge activity

• Mar 4, 8:32 PM UTC: A user started a stack merge that includes this pull request via Graphite.
• Mar 4, 8:34 PM UTC: Graphite rebased this pull request as part of a merge.
• Mar 4, 8:43 PM UTC: @vinistock merged this pull request with Graphite.

[Morriar]

The test covers every definition type (constants, ivars, class vars, attrs, methods) except alias new_name old_name (Definition::MethodAlias), whose callsite was also updated on line 512. Any chance we can add one more assertion here?

Suggested change

	assert_declaration_exists!(context, "Foo#initialize()");
	assert_declaration_exists!(context, "Foo#initialize()");
	assert_declaration_exists!(context, "Foo#bar()"); // alias bar initialize
	}

With a matching alias bar initialize added to the module ALIAS body.

[vinistock]

#642