fix(encoding/yaml): fix parseAll type definition by using overloads

[FujiHaruka]

fix #679

This fixes type definition of parseAll in yaml module.

Current:

// ok
parseAll(yaml)
// ok
parseAll(yaml, callback)
// ok
parseAll(yaml, callback, options)
// typing is ok, but options are ignored
parseAll(yaml, undefined, options)
// type error, but options are accepted
parseAll(yaml, options)

Modified:

// ok
parseAll(yaml)
// ok
parseAll(yaml, callback)
// ok
parseAll(yaml, callback, options)
// type error
parseAll(yaml, undefined, options)
// ok
parseAll(yaml, options)

[kt3k]

@FujiHaruka LGTM. Thanks!