Creating database using postgres

[ibotlold]

SQLAlchemy fails to start postgres dialect after the dialect is completely removed (discussion) According postgres documentation connection string should use postgresql. Current PR #100 does not provide changes is modules/database.py file.

In Postgres 15 changed default permission on public schema. It is now necessary grant permissions explicitly. Implemented this behaviour. Closes https://github.com/OpenSIPS/opensips/issues/3120

Changes

• changed postgres to postgresql in connection strings
• add legacy support to postgres database schema folder until main repo move files to postgresql folder
• grant access to public schema for database user
• update docs & test to postgresql usage

[liviuchircu]

Hi, @ibotlold! Thanks for providing some context, as well as references to #100 and #3120.

Rather than continuing to rely on this postgres backend naming possibly out of fear of not breaking things, let's see exactly what breaks after we switch to postgresql, per the recommendations of SQLAlchemy itself. I'd much rather address those types of "fresh" issues, than to keep rotting opensips-cli code & configuration which is slowly becoming obsolete with each new Debian release, for example.

Merging, cheers!