Add function redefine, other small changes for functions

[krishnangovindraj]

Usage and product changes

Adds function redefine syntax, and some small changes.

Implementation

• Add function redefine
• Makes some fields public
• Hack: Functions keep their unparsed string representation so the function manager can store it.

[typedb-bot]

PR Review Checklist

Do not edit the content of this comment. The PR reviewer should simply update this comment by ticking each review item below, as they get completed.

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Trivial Change

• This change is trivial and does not require a code or architecture review.

Code

• Packages, classes, and methods have a single domain of responsibility.
• Packages, classes, and methods are grouped into cohesive and consistent domain model.
• The code is canonical and the minimum required to achieve the goal.
• Modules, libraries, and APIs are easy to use, robust (foolproof and not errorprone), and tested.
• Logic and naming has clear narrative that communicates the accurate intent and responsibility of each module (e.g. method, class, etc.).
• The code is algorithmically efficient and scalable for the whole application.

Architecture

• Any required refactoring is completed, and the architecture does not introduce technical debt incidentally.
• Any required build and release automations are updated and/or implemented.
• Any new components follows a consistent style with respect to the pre-existing codebase.
• The architecture intuitively reflects the application domain, and is easy to understand.
• The architecture has a well-defined hierarchy of encapsulated components.
• The architecture is extensible and scalable.

[krishnangovindraj]

Flag the hack

[krishnangovindraj]

Flag a hack.
I'm supposed to use the span for this. But then I have to pass the unparsed query in the core functions.
I'm not sure whether I want to do that today or leave this in as a hack.