Make Performance/FlatMap aware of safe navigation operator

[ydakuka]

Describe the solution you'd like

# bad
def my_method
  [1, 2, 3, 4]&.map { |e| [e, e] }&.flatten(1)
end

Rubocop

ydakuka@yauhenid:~/Work/project$ bin/rails_docker rubocop -V
1.58.0 (using Parser 3.2.2.4, rubocop-ast 1.30.0, running on ruby 2.7.8) [x86_64-linux]
  - rubocop-capybara 2.19.0
  - rubocop-factory_bot 2.24.0
  - rubocop-performance 1.19.1
  - rubocop-rails 2.22.2
  - rubocop-rake 0.6.0
  - rubocop-rspec 2.25.0
  - rubocop-thread_safety 0.5.1