Add rubocop

Gemfile

@@ -1,9 +1,12 @@
+# frozen_string_literal: true
+
 source 'https://rubygems.org'
 gem 'cocoapods', '~> 1.10'
 gem 'fastlane', '~> 2'
-gem 'fastlane-plugin-wpmreleasetoolkit', '~> 5.0'
-gem 'fastlane-plugin-sentry', '~> 1.6'
 gem 'fastlane-plugin-appcenter', '~> 1.11'
+gem 'fastlane-plugin-sentry', '~> 1.6'
+gem 'fastlane-plugin-wpmreleasetoolkit', '~> 5.0'
+gem 'rubocop', '~> 1.38'
 
 group :screenshots, optional: true do
   gem 'rmagick', '~> 3.2.0'

Gemfile.lock

@@ -14,6 +14,7 @@ GEM
       httpclient (~> 2.8, >= 2.8.3)
       json (>= 1.5.1)
     artifactory (3.0.15)
+    ast (2.4.2)
     atomos (0.1.3)
     aws-eventstream (1.2.0)
     aws-partitions (1.655.0)
@@ -257,16 +258,20 @@ GEM
     optparse (0.1.1)
     os (1.1.4)
     parallel (1.22.1)
+    parser (3.1.2.1)
+      ast (~> 2.4.1)
     plist (3.6.0)
     progress_bar (1.3.3)
       highline (>= 1.6, < 3)
       options (~> 2.3.0)
     public_suffix (4.0.7)
     racc (1.6.0)
+    rainbow (3.1.1)
     rake (13.0.6)
     rake-compiler (1.2.0)
       rake
     rchardet (1.8.0)
+    regexp_parser (2.6.0)
     representable (3.2.0)
       declarative (< 0.1.0)
       trailblazer-option (>= 0.1.1, < 0.2.0)
@@ -275,7 +280,20 @@ GEM
     rexml (3.2.5)
     rmagick (3.2.0)
     rouge (2.0.7)
+    rubocop (1.38.0)
+      json (~> 2.3)
+      parallel (~> 1.10)
+      parser (>= 3.1.2.1)
+      rainbow (>= 2.2.2, < 4.0)
+      regexp_parser (>= 1.8, < 3.0)
+      rexml (>= 3.2.5, < 4.0)
+      rubocop-ast (>= 1.23.0, < 2.0)
+      ruby-progressbar (~> 1.7)
+      unicode-display_width (>= 1.4.0, < 3.0)
+    rubocop-ast (1.23.0)
+      parser (>= 3.1.1.0)
     ruby-macho (2.5.1)
+    ruby-progressbar (1.11.0)
     ruby2_keywords (0.0.5)
     rubyzip (2.3.2)
     sawyer (0.9.2)
@@ -332,6 +350,7 @@ DEPENDENCIES
   fastlane-plugin-sentry (~> 1.6)
   fastlane-plugin-wpmreleasetoolkit (~> 5.0)
   rmagick (~> 3.2.0)
+  rubocop (~> 1.38)
 
 BUNDLED WITH
    2.3.12