mojatax: Implement post and generic request function

[hunterachieng]

Summary

This is the implementation of a new adaptor mojatax

Fixes #773

Details

A new basic adaptor mojatax has been created with a simple post function to create an invoice and a generic request function for any other HTTP methods

AI Usage

Please disclose how you've used AI in this work (it's cool, we just want to know!):

• Code generation (copilot but not intellisense)
• Learning or fact checking
• Strategy / design
• Optimisation / refactoring
• Translation / spellchecking / doc gen
• Other
• I have not used AI

You can read more details in our Responsible AI Policy

Review Checklist

Before merging, the reviewer should check the following items:

• Does the PR do what it claims to do?
• If this is a new adaptor, added the adaptor on marketing website ?
• Are there any unit tests?
• Is there a changeset associated with this PR? Should there be? Note that
  dev only changes don't need a changeset.
• Have you ticked a box under AI Usage?

[josephjclark]

Nice and simple Hunter! Just a couple of little comments