Deprecate and/or remove RSA-SHA256-TLSSecret

See torspec#251 (closed) and tor#40874.

This is likely to have a torspec component.

@ahf - I think you mentioned this; did you want to do it?

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assigned to @nickm

I think it would be interesting to get rid of in C Tor, yeah. It could be something we do in the near future. It's not something I have to do with all the other smaller things I have on my plate.

added Doing label and removed Backlog label

Notes:

• The spec already says that this authentication method is obsolete.
• The method ("LinkAuth=1") is neither recommended or in consensus subprotocol versions.
• The successor method ("LinkAuth=3") is listed in required-relay-protocols.

mentioned in merge request !862 (merged)

added 6h of time spent

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mentioned in issue #41027

See also #41027.

added Needs Review label and removed Doing label

mentioned in commit db1709dc

mentioned in commit 742dbae9

closed with commit d83fcbf2

closed with merge request !862 (merged)