[Feature Request] Schema Aliases and Versioned Schemas

Dear PostgreSQL Development Team,

I’d like to propose a new feature for consideration: schema aliases and
versions

**Problem Statement:**
For migrating old db to new one, one must use an external tool or define a
dedicated migration script where all possible issues could arise

**Proposed Solution:**
there is two ways I may think about
- versioned schemas : where every version act as a separate schema and the
`latest` one or the one the program request is the one in use and each new
schema could inherit a table, index, view, ... without additional data
- aliases : where every new schema is defined and migrated separately then
an alias is set for the one in use

**Benefits:**
- migration process for under dev projects will be more easier
- App env stability, where no data need to be changed in the app other than
the logic of newly modified schema, not the connection nor the schema or db
name
- no need for external tools or servers to migrate or rollback
- minimal downtime between migrations and rollback

**why I post here**
it's addition to core pgsql
>> if it's not the right place : I could contact the mailing list you know
it's supposed to take feature requests

Thank you for considering this feature request.
I look forward to feedback or further discussion on this idea.

Best regards,
Abdelaziz sharaf