Clear out old TS rules and functions

[philsturgeon]

Go on a delete-spree taking away all of the old TS ruleset stuff.

• Spectral.addRules()
• Spectral.addFunctions()
• src/rulesets/oas/index.ts
• src/rulesets/oas2/index.ts
• src/rulesets/oas3/index.ts
• src/types/rule.ts
• anything else?

Whenever this gets done, it means the next release will need to be v5.0.

[philsturgeon]

@nulltoken if you want to start nuking bits I would really appreciate that. It would solve the confusion in #677.

[nulltoken]

@philsturgeon Let me see what I can come up with.

[nulltoken]

@philsturgeon Let me see what I can come up with.

So... I've started to chew on #689. It may not cover all the scope of this issue but should definitely hit "the one ruleset to rule them all" topic from #677 (comment) (in a backward compatible way).

To start with, I'm going to learn a bit from the failing tests that are going to break. Then I might ping @P0lip when I've got a rough proposal of what I'd like to propose.

[P0lip]

Then I might ping @P0lip when I've got a rough proposal of what I'd like to propose.

Sure thing @nulltoken. As always, I'm happy to help. :)
LMK once you have anything you'd like to share. Good luck!
Huge thanks for your contribution. ❤️

[P0lip]

Done in #773