Introduce primary keys for all tables in the APIM schema

[nuwand]

Some tables in the APIM schema including some IDN_ tables are missing primary keys. This becomes a problem for multi master data replication. Therefore we need to make sure all tables have primary keys in the APIM schema.

[rizmir22]

Related issue: Primary keys need to be fixed in the registry tables as well.
Public Jira: https://wso2.org/jira/browse/CARBON-16157

[uvindra]

Even adding a unique constraint to an existing column where suitable would suffice. In that case we dont have to add a new column as a primary key. The requirement is to have a column that is indexed(both primary keys and unique constraints cause indexes to be created)