Update metadata license identifiers to note presence or absence of RFN

Now that SPDX 3.8+ has added license variants(1) to easily distinguish between OFL-with-an-RFN and OFL-without-an-RFN, it would be helpful to update the license strings in the metadata files to reflect which applies to each font. I believe it would only be necessary to update the metadata files; touching the license files is not required.

Even though new fonts aren't accepted if they include an RFN, some older ones are already there, and making that difference harder to miss should reduce incidents where users or downstream projects accidentally overlook the presence of the RFN.

1. https://github.com/spdx/license-list-XML/pull/965