Create migration for column position change if a field position is changed in spec

[SOHELAHMED7]

Only for MySQL and MariaDB

Generate alter column position migration for MySQL and MariaDB if a field position(of existing field/column) is changed in YAML (OpenAPI spec). If a column position is changed in OpenAPI and nothing else then its MySQL/Maria migration should be generated to alter column position.

Also:

• also handle column position in case of dropping a column (in down code -> add column) (for one or more columns)
  add a test for: a column change: data type + comment + position; all 3 are changed moved to Add a test for: a column change: data type + comment + position; all 3 are changed  #64

Part of cebe#122, #10