chore: ESLint fixes

[inferrinizzard]

Description

Fixes all outstanding ESLint issues as reported in #2555

Motivation and Context

Once #2555 is merged, the latest commit on the master branch will be in an unstable state. This PR aims to immediately resolve that by fixing all existing errors including:

• Standardising JSON formats
• Enforcing consistent import syntax
• Enforcing consistent naming schemes
• Replacing or intentionally commenting all uses of the any type
• Adding explicit values for enums (prefer strings)
• Add access modifiers on all class methods
• Adding return types on all functions
• Converting undefined or null or operators to nullish coalescing
• Remove all null assertions in favour of optional chaining
• Final formatting indentation pass

This PR also tags several sections of the codebase that are in need of a refactor, these are the major candidates:

1. CJSON
   a. This file is far too heavily nested and dense to easily grok
2. Circular imports
   a. There are ~5 major circular import cycles that need to be resolved
3. Strongly typed RendererOptions
   a. strongly typing RendererOptions (as well as a few other places) could help to alleviate some areas where types are currently unknown/unclear
   b. would additionally help users of quicktype-core as we could provide intellisense while writing options

Previous Behaviour / Output

N/a

New Behaviour / Output

N/a

How Has This Been Tested?

npm run lint now only comes back with warnings, no errors

Screenshots (if appropriate):