refactor: use org templates as default

[roleyfoley]

Description

Removes the per repo github templates in favour of the base org wide templates defined in https://github.com/hamlet-io/.github. Overrides can be applied using the same file names in a repo if required

Motivation and Context

Further standardises the template configuration across our repos

How Has This Been Tested?

Tested using Github

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• Refactor (non-breaking change which improves the structure or operation of the implementation)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Followup Actions

• None

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.
• None of the above.