Update `SSL_SERIALIZED_SESSION_CONFIG_BITFLAG` with new flags

[davidhorstmann-arm]

Add missing flags to SSL_SERIALIZED_SESSION_CONFIG_BITFLAG. Previously, the bitflag did not uniquely identify a possible structure of a serialized session, meaning that multiple different incompatible session structures could be serialized with the same header.

The options added are as follows:

• From TLS 1.3 work:
  • Server name indication
  • Early data
  • Record size limit
• Preexisting in TLS 1.2 code:
  • Keep peer certificate

PR checklist

Please tick as appropriate and edit the reasons (e.g.: "backport: not needed because this is a new feature")

• [ ] changelog provided, or not required
• [ ] backport #8823
• [ ] tests provided, or not required

Notes for the submitter

Please refer to the contributing guidelines, especially the checklist for PR contributors.

Help make review efficient:

• Multiple simple commits
  • please structure your PR into a series of small commits, each of which does one thing
• Avoid force-push
  • please do not force-push to update your PR - just add new commit(s)
• See our Guidelines for Contributors for more details about the review process.