Replace map + compact with filter_map

[MatheusRich]

Summary

Since Rails 7 requires Ruby > 2.7, I changed some recurrences of map + compact with filter_map. I took the liberty to change some occurrences in tests too.

Other Information

Here's an article about filter_map: https://blog.saeloun.com/2019/05/25/ruby-2-7-enumerable-filter-map.html

Benchmark

N = 1_00_000
enum = 1.upto(1_000)
Benchmark.bmbm do |x|
  x.report("select + map") {N.times {enum.select { |i| i.even? }.map{|i| i +1}}}
  x.report("map + compact") {N.times {enum.map { |i| i + 1 if i.even? }.compact}}
  x.report("filter_map") {N.times {enum.filter_map { |i| i + 1 if i.even? }}}
end
#
# Rehearsal -------------------------------------------------
# select + map    8.569651   0.051319   8.620970 (  8.632449)
# map + compact   7.392666   0.133964   7.526630 (  7.538013)
# filter_map      6.923772   0.022314   6.946086 (  6.956135)
# --------------------------------------- total: 23.093686sec
# 
#                     user     system      total        real
# select + map    8.550637   0.033190   8.583827 (  8.597627)
# map + compact   7.263667   0.131180   7.394847 (  7.405570)
# filter_map      6.761388   0.018223   6.779611 (  6.790559)

[adityapandit17]

@rafaelfranca this is really wrong with this merge.
When I raise a pull request with exact same changes you reject. But now you have merged the same chages
@dhh @eileencodes @tenderlove @georgeclaghorn this is really partial.
link to the pull request

this is the link to the pull request.