refactor: remove dead code

[0xClandestine]

Motivation:

We've got dead code throughout the repo.

Modifications:

• Used this tool to programmatically remove dead Solidity.

Result:

Dead code has been removed.

[0xClandestine]

Some of this shouldn't be removed, this branch is mostly meant to illustrate what's currently dead.

[wadealexc]

Files that we should NOT tweak:

• script/releases/Env.sol
  • This library interacts with Zeus ENV variables, so anytime we have release scripts that aren't using some ENV variables, the methods that fetch those will be "dead". Let's not remove this code; we'll want it when writing future release scripts.
• src/contracts/libraries/BytesLib.sol
  • This isn't our code, it's a common library written by Goncalo Sa. Let's not alter the code; it's easier to validate that it's the "standard version" if we keep it as-is.
• Anything in test/integration/deprecatedInterfaces
  • It's dead now, but if we decide we need it, it's much more of a pain in the ass to re-implement/lookup old interfaces