Expand Lint/Void to catch other void contexts, specifically inside if statements

[jez]

Is your feature request related to a problem? Please describe.

Version

❯ rubocop -V
1.57.2 (using Parser 3.2.2.4, rubocop-ast 1.30.0, running on ruby 2.7.2) [arm64-darwin22]

foo.rb

# frozen_string_literal: true

def example
  ''
  if T.unsafe(true)
    puts
    ''
  end
  nil
end

Output

❯ rubocop foo.rb
Inspecting 1 file
W

Offenses:

foo.rb:4:3: W: [Correctable] Lint/Void: Literal '' used in void context.
  ''
  ^^

1 file inspected, 1 offense detected, 1 offense autocorrectable

In this example, we see that the '' on the first line of the example method reports a Lint/Void violation.

Describe the solution you'd like

The '' inside the if is also useless—it would be nice to have a rule which catches problems like this. This sort of code usually indicates that someone expected to be assigning '' to a variable, but no assignment is happening.

Describe alternatives you've considered

One solution would be adding this to Lint/Void.
Another solution would be creating a new rule for this.

Additional context

n/a