Add support for the Airbyte sources fields validations

[taletski]

Problem

Airbyte source configuration spec may contain restrictions for some fields i.e. regex pattern for strings or min/max for integers.

Initial attempt to embed those validations in the UI failed. Triggering the whole form validation by clicking Save or Test Connection buttons cleared all the fields values except for the invalid one.

Solution

Need to eliminate the buggy validation behaviour.

[vklimontovich]

Let also add custom transformations of Airbyte source config before sending it to server. CC @jfk9w