Use a better method name to check the requirement of password confirmation

Also improve changelog entries related to secure password to proper
highlight.
Make change_table use object of current database adapter

  - Earlier, change_table was creating database-agnostic object.
  - After this change, it will create correct object based on current
    database adapter.
  - This will ensure that create_table and change_table will get same objects.
  - This makes update_table_definition method public and nodoc.
  - Fixes #13577 and #13503
Merge pull request #13597 from prathamesh-sonpatki/hstore_migration

Make change_table use object of current database adapter
Fix typo in image_tag documentation

image_tag only supports :alt and :size as additional keys, not three.
Merge pull request #13621 from Intrepidd/patch-1

Fix typo in image_tag documentation [ci skip]