feat: eliminate unused imports

[mnahkies]

• uses hacky method of filtering out imports based on crude tokenization
• includes cli parameter escape hatch to turn off in-case it's buggy

tried using biome first, with some code like this (private methods used):

 // @ts-ignore
    const linted = biome.withFile(filename, raw, (path) => {
      // @ts-ignore
      const result = biome.workspace.fixFile({
        path,
        fix_file_mode: "SafeAndUnsafeFixes",
        should_format: false
      })
      return result.code
    })

but this was ludicrously slow, even with all rules apart from unused imports disabled

[mnahkies]

This removes the need to import from koa-body to keep typescript happy