Discourage the use of writer methods with rescued exceptions

ref: https://github.com/rubocop/rubocop/issues/13588

This is a little-known (I believe) and rarely used feature of the rescue operator, which allows assigning an exception using an object's writer method:

Foo = Struct.new(:exception)
foo = Foo.new

begin
  do_something_that_might_raise
rescue => foo.exception # `Foo#exception=` will be called
  Rails.error.report(foo.exception)
  do_something_with_exception(foo.exception)
end

I propose introducing a new cop that detects such patterns and suggests expanding them to

Foo = Struct.new(:exception)
foo = Foo.new

begin
  do_something_that_might_raise
rescue => e
  foo.exception = e # if required
  Rails.error.report(e)
  do_something_with_exception(e)
end

This cop could also support an alternative style that, conversely, suggests using the writer variant (where applicable).

Start with the referenced RuboCop issue 13588 and the two rescue examples in this issue. Clarify whether the proposed cop should support both writer and non-writer styles, then identify the appropriate RuboCop implementation and test locations. Done means the behavior and preferred style are specified and covered by tests.