Find an upgrade path from pyjwkest to PyJWT

[timmc-edx]

We're trying to discontinue use of pyjwkest: openedx/edx-drf-extensions#290 PyJWT looks like the best candidate, but the RSA key format requirements are stricter, so we wouldn't be able to use our current keys (at least, if they look like the keys the unit tests use).

Partial PR, showing the changes that would be required: #31829

Look into upgrade paths. Some options:

• Make our keys forward-compatible
• Provision multiple keys and select which one to use based on which library is present
• Figure out how to convert the keys on the fly at startup

[timmc-edx]

Suggested a path forward here: #31829 (comment)

[robrap]

Adding @iamsobanjaved so everyone is participating in this ticket.

[robrap]

Would there be a simple way to try all keys with all libraries, and succeed if anything succeeds?

[timmc-edx]

Decision: We're going to make the keys forward-compatible before making the code change. This might mean adjusting the existing keys or doing a key rotation.