Apply Rails/DynamicFindBy rubocop rule

We were already using `find_by` most of the time.

Since there are false positives related to our `find_by_slug_or_id!` and
`find_by_manger_login` methods, which cannot be replaced with `find_by`,
I'm adding it indicating the "refactor" severity.

.rubocop_basic.yml

@@ -156,6 +156,10 @@ Rails/ApplicationRecord:
 Rails/Date:
   Enabled: true
 
+Rails/DynamicFindBy:
+  Enabled: true
+  Severity: refactor
+
 Rails/FindBy:
   Enabled: true
 

app/models/budget/phase.rb

@@ -30,7 +30,7 @@ class Budget
     scope :published,         -> { enabled.where.not(kind: "drafting") }
 
     PHASE_KINDS.each do |phase|
-      define_singleton_method(phase) { find_by_kind(phase) }
+      define_singleton_method(phase) { find_by(kind: phase) }
     end
 
     def next_enabled_phase

app/models/concerns/sluggable.rb

@@ -5,11 +5,11 @@ module Sluggable
     before_validation :generate_slug, if: :generate_slug?
 
     def self.find_by_slug_or_id(slug_or_id)
-      find_by_slug(slug_or_id) || find_by_id(slug_or_id)
+      find_by(slug: slug_or_id) || find_by(id: slug_or_id)
     end
 
     def self.find_by_slug_or_id!(slug_or_id)
-      find_by_slug(slug_or_id) || find(slug_or_id)
+      find_by(slug: slug_or_id) || find(slug_or_id)
     end
   end
 

config/initializers/i18n_translation.rb

@@ -9,7 +9,7 @@ module ActionView
       def t(key, options = {})
         current_locale = options[:locale].presence || I18n.locale
 
-        i18_content = I18nContent.find_by_key(key)
+        i18_content = I18nContent.find_by(key: key)
         translation = I18nContentTranslation.where(i18n_content_id: i18_content&.id,
                                                    locale: current_locale).first&.value
         translation.presence || translate(key, options)

db/pages/accessibility.rb

@@ -1,4 +1,4 @@
-if SiteCustomization::Page.find_by_slug("accessibility").nil?
+if SiteCustomization::Page.find_by(slug: "accessibility").nil?
   page = SiteCustomization::Page.new(slug: "accessibility", status: "published")
   page.title = I18n.t("pages.accessibility.title")
 

db/pages/conditions.rb

@@ -1,4 +1,4 @@
-if SiteCustomization::Page.find_by_slug("conditions").nil?
+if SiteCustomization::Page.find_by(slug: "conditions").nil?
   page = SiteCustomization::Page.new(slug: "conditions", status: "published")
   page.print_content_flag = true
   page.title = I18n.t("pages.conditions.title")

db/pages/faq.rb

@@ -1,4 +1,4 @@
-if SiteCustomization::Page.find_by_slug("faq").nil?
+if SiteCustomization::Page.find_by(slug: "faq").nil?
   page = SiteCustomization::Page.new(slug: "faq", status: "published")
   page.title = I18n.t("pages.help.faq.page.title")
   page.content = "<p>#{I18n.t("pages.help.faq.page.description")}</p>"

db/pages/privacy.rb

@@ -1,4 +1,4 @@
-if SiteCustomization::Page.find_by_slug("privacy").nil?
+if SiteCustomization::Page.find_by(slug: "privacy").nil?
   page = SiteCustomization::Page.new(slug: "privacy", status: "published")
   page.print_content_flag = true
   page.title = I18n.t("pages.privacy.title")

db/pages/welcome_level_three_verified.rb

@@ -1,4 +1,4 @@
-if SiteCustomization::Page.find_by_slug("welcome_level_three_verified").nil?
+if SiteCustomization::Page.find_by(slug: "welcome_level_three_verified").nil?
   page = SiteCustomization::Page.new(slug: "welcome_level_three_verified", status: "published")
   page.title = I18n.t("welcome.welcome.title")
 

db/pages/welcome_level_two_verified.rb

@@ -1,4 +1,4 @@
-if SiteCustomization::Page.find_by_slug("welcome_level_two_verified").nil?
+if SiteCustomization::Page.find_by(slug: "welcome_level_two_verified").nil?
   page = SiteCustomization::Page.new(slug: "welcome_level_two_verified", status: "published")
   page.title = I18n.t("welcome.welcome.title")
 

db/pages/welcome_not_verified.rb

@@ -1,4 +1,4 @@
-if SiteCustomization::Page.find_by_slug("welcome_not_verified").nil?
+if SiteCustomization::Page.find_by(slug: "welcome_not_verified").nil?
   page = SiteCustomization::Page.new(slug: "welcome_not_verified", status: "published")
   page.title = I18n.t("welcome.welcome.title")
 

spec/features/admin/site_customization/pages_spec.rb

@@ -25,7 +25,7 @@ describe "Admin custom pages" do
 
       expect(SiteCustomization::Page.count).to be 7
       slugs.each do |slug|
-        expect(SiteCustomization::Page.find_by_slug(slug).status).to eq "published"
+        expect(SiteCustomization::Page.find_by(slug: slug).status).to eq "published"
       end
 
       expect(all("[id^='site_customization_page_']").count).to be 7