fix(packages/cli): revert ESM

[Zidious]

This PR reverts the recent conversion to ESM for CLI as it's not required which should fix the pathing for the CLI binary when looking for the axe-core source.

Closes: #729
Closes: #726

[stephenmathieson]

Does this need to be more complicated than:

export const getAxeSource = (axePath = require.resolve('axe-core')): string => {
  return fs.readFileSync(axePath, 'utf-8')
}

...and if not, do we really need this function?

[stephenmathieson]

LGTM, but as said before, there was probably a reason we did funky path lookups. Please make sure that there isn't some obscure requirement we're breaking by using require.resolve().

[stephenmathieson]

Should we remove the ESM stuff in the CLI package (since it's not used/needed)?

[michael-siek]

I think we should not support ESM in CLI

[Zidious]

I think we should not support ESM in CLI

I am in favour of that - but IMO it should happen outside of this PR