Add go modules (go.mod) to golang section detection

[matchai]

Description

Added go.mod file to golang section detection.

Also happened to rework a few other tests as I wasn't happy with tests defaulting to sections being enabled by the dependant files being added in the setup step.

Motivation and Context

Ports the following PR to spaceship: https://github.com/denysdovhan/spaceship-prompt/pull/559

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

How Has This Been Tested?

• [x] I have tested using MacOS
• [ ] I have tested using Linux

Checklist:

• [x] I have checked that no other PR duplicates mine
• [x] My code follows the code style of this project.
• [x] My change requires a change to the documentation.
• [x] I have updated the documentation accordingly.
• [x] I have updated the tests accordingly.