Hide service methods

[Tigrov]

Make them private / protected or hide behind a proxy like $model->activeRecord()->propertyNames() (see #388)

ActiveRecordInterface::

• propertyNames()
• propertyValues()
• oldValue()
• primaryKeyOldValue()
• primaryKeyOldValues()
• tableSchema()
• relatedRecords() ?
• hasMany()
• hasOne()
• resetRelation()
• oldValues()
• newValues() ?
• assignOldValue()
• assignOldValues()

ActiveQueryInterface::getTablesUsedInFrom() and QueryInterface::getTablesUsedInFrom()