Make some cops aware of safe navigation operator

[koic]

Fixes #403, #404, #405, #406, #408, #411, #412, #413, #415, #416, and #417.

This PR makes Performance/Count, Performance/FixedSize, Performance/FlatMap, Performance/InefficientHashSearch, Performance/RangeInclude, Performance/RedundantSortBlock, Performance/ReverseFirst, Performance/SelectMap, Performance/Size Performance/SortReverse, and Performance/TimesMap cops aware of safe navigation operator.

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Before submitting the PR make sure the following are checked:

• The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
• Wrote good commit messages.
• Commit message starts with [Fix #issue-number] (if the related issue exists).
• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Ran bundle exec rake default. It executes all tests and runs RuboCop on its own code.
• Added an entry (file) to the changelog folder named {change_type}_{change_description}.md if the new code introduces user-observable changes. See changelog entry format for details.

[ydakuka]

@koic

There seems to be an error.

ydakuka@yauhenid:~$ irb
2.7.6 :001 > 4&.times&.map(&:to_s)
 => ["0", "1", "2", "3"] 
2.7.6 :002 > Array.new(4) { |i| i.to_s }
 => ["0", "1", "2", "3"] 

2.7.6 :003 > nil&.times&.map(&:to_s)
 => nil 
2.7.6 :004 > Array.new(nil) { |i| i.to_s }
Traceback (most recent call last):
        6: from /home/ydakuka/.rvm/rubies/ruby-2.7.6/bin/irb:23:in `<main>'
        5: from /home/ydakuka/.rvm/rubies/ruby-2.7.6/bin/irb:23:in `load'
        4: from /home/ydakuka/.rvm/rubies/ruby-2.7.6/lib/ruby/gems/2.7.0/gems/irb-1.2.6/exe/irb:11:in `<top (required)>'
        3: from (irb):4
        2: from (irb):4:in `new'
        1: from (irb):4:in `initialize'
TypeError (no implicit conversion from nil to integer)