Check field schema errors on makemigrations command

[bdragon300]

When user performs makemigrations command it's needed to check some incorrect states which a field could have. If error has detected then process should be interrupted with a message with advice.

For example, if a field at the same time has required=True flag and empty or null default.

Also this issue about to move AlterField._fix_field_params method to BaseFieldAction class and implement such schema check there.