Task: Add CI support for Oracle 18c

[code-ape]

Feature

This is a feature ticket to track the work of implementing the below changes.

Tagging user @lorefnon since this involved oracle
Tagging issue #4869 ("Inserting Buffers for Oracle CLOBs silently fails") since its resolution is blocked on this.

Use case

Knex CI for PRs should run full test suite again Oracle so that features may be properly validated.

Explain what kind of feature would support this

By adding automation to this repository and using the quillbuilduser/oracle-18-xe Docker container we can do a full Github Actions CI environment for Oracle 18c XE on Linux.

Acceptance Criteria

• A local Oracle 18c database can be stood up on a Linux machine using automation in this repository.
• This logic is used to run CI automation on PRs via Github Actions, as is standard with all other databases supported by Knex.
• All changes and use is documented.