feat: add protocol method for session/set_config_option

[gbtami]

Problem statement

While I asked Codex to migrate my Isaac ACP client/agent to 0.8.0 he created this https://github.com/gbtami/isaac/blob/main/src/isaac/acp_compat.py file.

Proposed solution

If he is correct and this is really needed, it should possible be handled in the SDK

Alternatives considered

No response

Additional context

No response

Can you help build it?

• I can contribute code or docs for this request.

[PsiACE]

thanks, i will check it later