Tidy up TorSettings documentation

In the rebase to ESR 140 a number of errors in the documentation for TorSettings.sys.mjs were caught by the linter and corrected.

I think I would want to make a few minor adjustments to the corrections:

1. Some get properties are missing their @type parameters.
2. #builtinBridges is documented as an opaque object, rather than a key-value map from string to string[].
3. @param {Function?} equal should be @param {Function?} [equal].