Augmented fuzzer dict for dns_record_fuzzer.cc to test OptRecordRdata.

Current fuzzer dict does not have any specific tests for OptRecordRdata
(and, by extension, any of new Opts added in a recent CL, specifically
Padding and EDE). Adding this will verify the robustness of the
implementation.

Bug: 1354174
Change-Id: I50fc873e6416128d2516c66d7f03dcb4e931e571
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3838814
Commit-Queue: Eric Orth <ericorth@chromium.org>
Reviewed-by: Dan McArdle <dmcardle@chromium.org>
Reviewed-by: Eric Orth <ericorth@chromium.org>
Auto-Submit: Sukrit Ganesh <sukritganesh@google.com>
Cr-Commit-Position: refs/heads/main@{#1037161}