Add and apply rules for multi-line hashes

For the HashAlignment rule, we're using the default `key` style (keys
are aligned and values aren't) instead of the `table` style (both keys
and values are aligned) because, even if we used both in the
application, we used the `key` style a lot more. Furthermore, the
`table` style looks strange in places where there are both very long and
very short keys and sometimes we weren't even consistent with the
`table` style, aligning some keys without aligning other keys.

Ideally we could align hashes to "either key or table", so developers
can decide whether keeping the symmetry of the code is worth it in a
case-per-case basis, but Rubocop doesn't allow this option.

spec/models/budget/phase_spec.rb

@@ -175,8 +175,8 @@ describe Budget::Phase do
     describe "when being enabled" do
       before do
         accepting_phase.update!(enabled: false,
-                             starts_at: Date.current,
-                             ends_at:  Date.current + 2.days)
+                                starts_at: Date.current,
+                                ends_at: Date.current + 2.days)
       end
 
       it "adjusts previous enabled phase end date to its own start date" do
@@ -211,16 +211,16 @@ describe Budget::Phase do
       it "doesn't adjust previous enabled phase end date to its own start date" do
         expect do
           accepting_phase.update(enabled: false,
-                              starts_at: Date.current,
-                              ends_at:  Date.current + 2.days)
+                                 starts_at: Date.current,
+                                 ends_at: Date.current + 2.days)
         end.not_to change { prev_enabled_phase.ends_at }
       end
 
       it "adjusts next enabled phase start date to its own start date" do
         expect do
           accepting_phase.update(enabled: false,
-                              starts_at: Date.current,
-                              ends_at:  Date.current + 2.days)
+                                 starts_at: Date.current,
+                                 ends_at: Date.current + 2.days)
         end.to change { next_enabled_phase.starts_at.to_date }.to(Date.current)
       end
     end