Add encrypted fields for plaintext tokens

What does this MR do and why?

Describe in detail what your merge request does and why.

Database

Migration

== 20211124132319 AddEncryptedStaticObjectsExternalStorageAuthToken: migrating
-- add_column(:application_settings, :static_objects_external_storage_auth_token_encrypted, :text)
   -> 0.0028s
-- transaction_open?()
   -> 0.0000s
-- current_schema()
   -> 0.0002s
-- transaction_open?()
   -> 0.0000s
-- execute("ALTER TABLE application_settings\nADD CONSTRAINT check_32710817e9\nCHECK ( char_length(static_objects_external_storage_auth_token_encrypted) <= 255 )\nNOT VALID;\n")
   -> 0.0049s
-- current_schema()
   -> 0.0002s
-- execute("SET statement_timeout TO 0")
   -> 0.0006s
-- execute("ALTER TABLE application_settings VALIDATE CONSTRAINT check_32710817e9;")
   -> 0.0020s
-- execute("RESET statement_timeout")
   -> 0.0007s
== 20211124132319 AddEncryptedStaticObjectsExternalStorageAuthToken: migrated (0.0317s)

== 20211124132522 AddEncryptedStaticObjectToken: migrating ====================
-- add_column(:users, :static_object_token_encrypted, :text)
   -> 0.0018s
-- transaction_open?()
   -> 0.0000s
-- current_schema()
   -> 0.0003s
-- transaction_open?()
   -> 0.0000s
-- execute("ALTER TABLE users\nADD CONSTRAINT check_7bde697e8e\nCHECK ( char_length(static_object_token_encrypted) <= 255 )\nNOT VALID;\n")
   -> 0.0017s
-- current_schema()
   -> 0.0002s
-- execute("ALTER TABLE users VALIDATE CONSTRAINT check_7bde697e8e;")
   -> 0.0015s
== 20211124132522 AddEncryptedStaticObjectToken: migrated (0.0128s) ===========

Rollback

== 20211124132522 AddEncryptedStaticObjectToken: reverting ====================
-- transaction_open?()
   -> 0.0000s
-- transaction_open?()
   -> 0.0000s
-- execute("ALTER TABLE users\nDROP CONSTRAINT IF EXISTS check_7bde697e8e\n")
   -> 0.0014s
-- remove_column(:users, :static_object_token_encrypted)
   -> 0.0012s
== 20211124132522 AddEncryptedStaticObjectToken: reverted (0.0120s) ===========

== 20211124132319 AddEncryptedStaticObjectsExternalStorageAuthToken: reverting
-- transaction_open?()
   -> 0.0000s
-- transaction_open?()
   -> 0.0000s
-- execute("ALTER TABLE application_settings\nDROP CONSTRAINT IF EXISTS check_32710817e9\n")
   -> 0.0017s
-- remove_column(:application_settings, :static_objects_external_storage_auth_token_encrypted)
   -> 0.0014s
== 20211124132319 AddEncryptedStaticObjectsExternalStorageAuthToken: reverted (0.0130s)

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