* uri: Add `UriError`
* uri: Throw `UriError` for unexpected failures in uri_parser_rfc3986
This is a follow-up for php/php-src#19779 which updated the error *messages*
for the non-syntax errors, but did not update the exception class, still
implying it's related to invalid URIs.
Given that we don't know ourselves if these are reachable in practice, they are
cannot be meaningfully handled by a user of PHP. Thus this should be a `Error`
according to our exception policy.
* uri: Throw `UriError` when unable to recompose URIs
* uri: Throw `UriError` when unable to read component
* NEWS