Add default_preferred_language to application_settings

What does this MR do and why?

In order to facilitate the database review, this MR is extracted from the !101621 (merged).

Add default_preferred_language to application_settings,

to allow administrators to set language preference for new users by configuring default_preferred_language.

Default behavior not changed, default preference is English "en".

Reference from doc: https://docs.gitlab.com/ee/development/database/strings_and_the_text_data_type.html

Migration log

Migrate

bundle exec rails db:migrate

main: == 20221101032521 AddDefaultPreferredLanguageToApplicationSettings: migrating =
main: -- add_column(:application_settings, :default_preferred_language, :text, {:default=>"en", :null=>false})
main:    -> 0.0065s
main: == 20221101032521 AddDefaultPreferredLanguageToApplicationSettings: migrated (0.0072s) 

main: == 20221101032600 AddTextLimitToDefaultPreferredLanguageOnApplicationSettings: migrating 
main: -- transaction_open?()
main:    -> 0.0000s
main: -- current_schema()
main:    -> 0.0005s
main: -- transaction_open?()
main:    -> 0.0000s
main: -- execute("ALTER TABLE application_settings\nADD CONSTRAINT check_e2692d7523\nCHECK ( char_length(default_preferred_language) <= 32 )\nNOT VALID;\n")
main:    -> 0.0020s
main: -- current_schema()
main:    -> 0.0004s
main: -- execute("SET statement_timeout TO 0")
main:    -> 0.0004s
main: -- execute("ALTER TABLE application_settings VALIDATE CONSTRAINT check_e2692d7523;")
main:    -> 0.0016s
main: -- execute("RESET statement_timeout")
main:    -> 0.0005s
main: == 20221101032600 AddTextLimitToDefaultPreferredLanguageOnApplicationSettings: migrated (0.0250s) 

ci: == 20221101032521 AddDefaultPreferredLanguageToApplicationSettings: migrating =
ci: -- add_column(:application_settings, :default_preferred_language, :text, {:default=>"en", :null=>false})
ci:    -> 0.0044s
ci: == 20221101032521 AddDefaultPreferredLanguageToApplicationSettings: migrated (0.0046s) 

ci: == 20221101032600 AddTextLimitToDefaultPreferredLanguageOnApplicationSettings: migrating 
ci: -- transaction_open?()
ci:    -> 0.0000s
ci: -- current_schema()
ci:    -> 0.0003s
ci: -- transaction_open?()
ci:    -> 0.0000s
ci: -- execute("ALTER TABLE application_settings\nADD CONSTRAINT check_e2692d7523\nCHECK ( char_length(default_preferred_language) <= 32 )\nNOT VALID;\n")
ci:    -> 0.0018s
ci: -- current_schema()
ci:    -> 0.0004s
ci: -- execute("SET statement_timeout TO 0")
ci:    -> 0.0004s
ci: -- execute("ALTER TABLE application_settings VALIDATE CONSTRAINT check_e2692d7523;")
ci:    -> 0.0013s
ci: -- execute("RESET statement_timeout")
ci:    -> 0.0005s
ci: == 20221101032600 AddTextLimitToDefaultPreferredLanguageOnApplicationSettings: migrated (0.0122s)

Rollback

bundle exec rails db:rollback:main STEP=2

main: == 20221101032600 AddTextLimitToDefaultPreferredLanguageOnApplicationSettings: reverting 
main: -- transaction_open?()
main:    -> 0.0000s
main: -- transaction_open?()
main:    -> 0.0000s
main: -- execute("            ALTER TABLE application_settings\n            DROP CONSTRAINT IF EXISTS check_e2692d7523\n")
main:    -> 0.0029s
main: == 20221101032600 AddTextLimitToDefaultPreferredLanguageOnApplicationSettings: reverted (0.0212s) 

main: == 20221101032521 AddDefaultPreferredLanguageToApplicationSettings: reverting =
main: -- remove_column(:application_settings, :default_preferred_language, :text, {:default=>"en", :null=>false})
main:    -> 0.0027s
main: == 20221101032521 AddDefaultPreferredLanguageToApplicationSettings: reverted (0.0051s) 

bundle exec rails db:rollback:ci STEP=2

ci: == 20221101032600 AddTextLimitToDefaultPreferredLanguageOnApplicationSettings: reverting 
ci: -- transaction_open?()
ci:    -> 0.0000s
ci: -- transaction_open?()
ci:    -> 0.0000s
ci: -- execute("            ALTER TABLE application_settings\n            DROP CONSTRAINT IF EXISTS check_e2692d7523\n")
ci:    -> 0.0025s
ci: == 20221101032600 AddTextLimitToDefaultPreferredLanguageOnApplicationSettings: reverted (0.0170s) 

ci: == 20221101032521 AddDefaultPreferredLanguageToApplicationSettings: reverting =
ci: -- remove_column(:application_settings, :default_preferred_language, :text, {:default=>"en", :null=>false})
ci:    -> 0.0024s
ci: == 20221101032521 AddDefaultPreferredLanguageToApplicationSettings: reverted (0.0046s)

---

/cc JH EM @prajnamas