Support scram-sha-256 out of the box

[julianladisch]

Remove <optional>true</optional> from com.ongres.scram:scram-client dependency in pom.xml.

Since PostgreSQL 14 the default value for password_encryption is scram-sha-256.

Explain the migration from Vert.x 4 to Vert.x 5 in index.adoc - the client has been changed from client to scram-client:
https://github.com/eclipse-vertx/vertx-sql-client/pull/1431/files

Fixes #944, #1059, #1189, #1249, #1266, #1398, #1466

Motivation:

The client fails with all default installations of PostgreSQL versions >= 14.

Conformance:

• You should have signed the Eclipse Contributor Agreement as explained in https://github.com/eclipse/vert.x/blob/master/CONTRIBUTING.md
• Please also make sure you adhere to the code style guidelines: https://github.com/vert-x3/wiki/wiki/Vert.x-code-style-guidelines

[vietj]

I think we need to remove the associated unit test for this MissingScramTest as well.

[vietj]

and check if other things need to be cleaned up

[julianladisch]

PostgreSQL has many client authentication methods: https://www.postgresql.org/docs/current/client-authentication.html
Scram authentication is one of them and is optional.
There can be valid uses cases where the client uses other auth methods only and the scram-client dependency is removed from the client to make the client as small as possible.
Therefore the code that handles a missing scram-client library in ScramAuthentication, InitCommandCodec and MissingScramTest should be kept.

[vietj]

good point, therefore I think we need to document this and say that the dependency can be excluded if that is needed in the documentation.

[julianladisch]

Aggreed, added that to the documentation.