BED-4153: slog Migration

[wes-mil]

Description

Migration to slog

Motivation and Context

This PR addresses:
BED-4153
BED-5056

Why is this change required? What problem does it solve?

slog is much more powerful than the previous logging solution and allows for contextual logging throughout the app.

How Has This Been Tested?

App build and runs locally. All tests passing.

Screenshots (optional):

Types of changes

• Chore (a change that does not modify the application functionality)
• Bug fix (non-breaking change which fixes an issue)

Checklist:

• I have met the contributing prerequisites
  • Assigned myself to this PR
  • Added the appropriate labels
  • Associated an issue: Issues and Pull Requests README #672
  • Read the Contributing guide: https://github.com/SpecterOps/BloodHound/wiki/Contributing
• I have ensured that related documentation is up-to-date
  • Open API docs
  • Code comments (GoDocs / JSDocs)
• I have followed proper test practices
  • Added/updated tests to cover my changes
  • All new and existing tests passed